Introduction
The Obsessive Compulsive Inventory (OCI) is a 42-item self-report questionnaire that measures how often obsessive-compulsive symptoms occur and how much distress they cause. Edna B. Foa and colleagues published it in 1998 in Psychological Assessment. They developed it to address problems in the instruments then available for assessing obsessive-compulsive disorder (OCD).
The original study has received at least 1,100 citations. Today, an 18-item revision, the Obsessive Compulsive Inventory-Revised (OCI-R), is more widely used. This guide focuses on the original 42-item OCI and explains its seven subscales, its dual frequency and distress scoring, and its validation evidence.
Key Features of the Obsessive Compulsive Inventory (OCI)
Purpose and Use
Foa and colleagues designed the OCI to address the problems inherent in existing instruments for determining the diagnosis and severity of OCD. As a result, it is a standardized self-report measure for screening symptom severity, monitoring treatment progress and supporting clinical evaluation.
However, the OCI is not a stand-alone diagnostic instrument. Instead, clinicians should use it alongside a comprehensive clinical interview and a professional psychological or psychiatric assessment.
Target Population
The original OCI targets adults. For younger people, researchers have evaluated a separate child version, described in the section on other versions below.
Structure
The OCI contains 42 items that form seven subscales:
Washing: excessive handwashing, bathing and cleaning rituals, fears of dirt, germs or contamination, and distress when rituals cannot be performed.Checking: repeated checking of doors, locks, appliances, belongings or completed tasks, and the need for reassurance because of persistent doubts, even when everything is objectively safe or correct.DoubtingOrdering: the need for order and exact symmetry, and discomfort when items feel "not quite right."Obsessing: intrusive, repetitive and unwanted thoughts, images or impulses that are difficult to control.Hoarding: difficulty discarding possessions regardless of their value, and accumulation that interferes with living spaces.Mental Neutralizing: mental rituals, such as silently repeating words or numbers, praying excessively or counting, to reduce anxiety.Across all dimensions, the inventory captures the frequency, intensity and distress of symptoms. In addition, it reflects how much they interfere with work, study, social life and personal functioning.
Scoring Method
Respondents rate every item twice: once for how often the symptom occurs (frequency) and once for how much it bothers them (distress). Both ratings use the same 5-point Likert scale:
Score
Rating
0
Not at all
1
A little
2
Moderately
3
A lot
4
Extremely
To score the OCI, follow these steps:
Record the frequency and distress ratings for every item.Sum all frequency ratings to obtain the Total Frequency Score (0–168).Sum all distress ratings to obtain the Total Distress Score (0–168).Sum the items within each of the seven subscales, separately for frequency and distress.No items are reverse scored. Therefore, higher scores indicate more frequent symptoms, greater distress, or both. Overall, the OCI quantifies symptom severity and tracks change over time; it does not provide a diagnosis.
Administration Format
The OCI is a self-report questionnaire, so respondents complete it themselves. Specifically, they give two ratings for each of the 42 items, one for frequency and one for distress.
Applications of the Obsessive Compulsive Inventory (OCI)
The OCI serves several roles in clinical practice and research:
Screening: estimating the severity of obsessive-compulsive symptoms.Symptom profiling: identifying a person's predominant symptom dimensions across the seven subscales.Monitoring: tracking changes in symptom frequency and distress during treatment.Supporting clinical evaluation: adding standardized data to a comprehensive clinical interview.Languages and availability
Researchers have adapted and studied the OCI in several languages:
Italian: a validation in community and clinical samplesJapanese: the development and validation of a Japanese versionPortugueseGerman: a 12-item version (OCI-12) validated in clinical and non-clinical samplesThe OCI is free for non-commercial research and clinical use. However, permission may be required for reproduction, translation, modification or commercial use.
Reliability and Validity
Foa and colleagues validated the OCI as a new OCD scale in their 1998 study. Since then, other researchers have examined its psychometric properties in Italian community and clinical samples and developed a validated Japanese version.
Validation studies:
The validation of a new obsessive–compulsive disorder scale: The Obsessive–Compulsive Inventory (1998): study linkThe Italian version of the Obsessive Compulsive Inventory: its psychometric properties on community and clinical samples (2009): study linkDevelopment and validation of the Japanese version of the Obsessive-Compulsive Inventory (2014): study linkLimitations and Considerations
Keep the following points in mind when using the OCI:
Not a diagnostic tool: the OCI supports, but cannot replace, a comprehensive clinical interview and professional assessment.Length: the original version has 42 items rated twice, whereas the 18-item OCI-R is quicker to administer.Adults only: the original version targets adults; children need the child version.Permissions: reproduction, translation, modification or commercial use may require permission.Other Versions And Related Questionnaires
Several versions of the OCI exist for different needs:
Obsessive-Compulsive Inventory–Revised (OCI-R): an 18-item version; read the ResRef OCI-R guide or the NovoPsych overview.Obsessive Compulsive Inventory – Child Version (OCI-CV): further evaluated in clinical samples.German 12-item OCI (OCI-12): translated and validated in clinical and non-clinical samples.In addition, these questionnaires are similar or complementary to the OCI:
Yale–Brown Obsessive Compulsive Scale (Y-BOCS)Padua Inventory (PI)Maudsley Obsessive-Compulsive Inventory (MOCI)Dimensional Obsessive-Compulsive Scale (DOCS)Additional Resources
The original article record on APA PsycNet: linkYou can access the questionnaire as a PDF through this linkFor inquiries, contact Edna B. Foa at foa@mail.med.upenn.edu.Browse more psychiatry questionnaires in the ResRef database.Frequently Asked Questions (FAQ)
What does the Obsessive Compulsive Inventory measure?The OCI measures the frequency of obsessive-compulsive symptoms and the distress they cause across seven subscales: washing, checking, doubting, ordering, obsessing, hoarding and mental neutralizing.
How is the OCI scored?Each of the 42 items receives a frequency rating and a distress rating from 0 to 4. Summing them gives a Total Frequency Score and a Total Distress Score, each ranging from 0 to 168.
Can the OCI diagnose OCD?No. The OCI is not a stand-alone diagnostic instrument. Clinicians should use it alongside a comprehensive clinical interview and a professional psychological or psychiatric assessment.
What is the difference between the OCI and the OCI-R?The original OCI has 42 items rated for both frequency and distress. The revised OCI-R has 18 items, is quicker to administer, and is now the more widely used form.
Is the OCI free to use?The OCI is free for non-commercial research and clinical use. However, reproduction, translation, modification or commercial use may require permission from the authors or publisher.
A Word from ResRef About the Obsessive Compulsive Inventory (OCI)
The Obsessive-Compulsive Inventory is a self-report screening tool designed to assess obsessive-compulsive symptoms across multiple dimensions. It exists in two primary forms: the original 42-item version (measuring both symptom frequency and distress) and the more widely used 18-item revised version (OCI-R), which is quicker to administer while maintaining strong psychometric properties.
References
Foa, E. B., Kozak, M. J., Salkovskis, P. M., Coles, M. E., & Amir, N. (1998). The validation of a new obsessive–compulsive disorder scale: The Obsessive–Compulsive Inventory. Psychological Assessment, 10(3), 206–214. https://doi.org/10.1037/1040-3590.10.3.206Sica, C., Ghisi, M., Altoè, G., Chiri, L. R., Franceschini, S., Coradeschi, D., & Melli, G. (2009). The Italian version of the Obsessive Compulsive Inventory: Its psychometric properties on community and clinical samples. Journal of Anxiety Disorders, 23(2), 204–211. https://doi.org/10.1016/j.janxdis.2008.07.001Ishikawa, R., Kobori, O., & Shimizu, E. (2014). Development and validation of the Japanese version of the obsessive-compulsive inventory. BMC Research Notes, 7(1). https://doi.org/10.1186/1756-0500-7-306Aspvall, K., Cervin, M., Andrén, P., Perrin, S., Mataix-Cols, D., & Andersson, E. (2020). Validity and clinical utility of the obsessive compulsive inventory - child version: further evaluation in clinical samples. BMC Psychiatry, 20(1). https://doi.org/10.1186/s12888-020-2450-7Müller, C. L., Fink-Lamotte, J., Jelinek, L., Lohse, L., Ehring, T., Noll-Hussong, M., Berberich, G., Wahl-Kordon, A., Borgelt, J., McKay, D., Abramowitz, J. S., Abramovitch, A., & Cludius, B. (2025). Translation and validation of the German 12-item Obsessive-Compulsive Inventory (OCI-12) in clinical and non-clinical samples. Clinical Psychology in Europe, 7(4). https://doi.org/10.32872/cpe.16165