. Introduction Obsessive compulsive disorder (OCD) is a chronic and disabling condition, often showing an early onset (1). OCD has been extensively studied in adults, adolescents, and children, but a critial gap remains in the clinical characterization of older patients (2). The present study was aimed to assess prevalence of geriatric OCD (G-OCD ≥ 65 years) and associated sociodemographic and clinical correlates of geriatric OCD in a large international sample of OCD patients. Methods Data of 416 outpatients recruited by different OCD Clinics worldwide, participating in the International College of Obsessive-compulsive Spectrum Disorders (ICOCS) network (3), were assessed and first categorized into 2 groups, age < 65 years vs ≥ 65 years, and then categorized on the basis of the median age of the whole sample (age < 42 years vs age ≥ 42 years) and their sociodemographic and clinical variables compared through Pearson Chi-squared and t tests for categorical and continuous variables. Results Patients with G-OCD represented a significant minority of the overall sample (n=24, 6% of the total sample vs age<65 years: n=392 (94% of the total sample) p<.001). Patients with G-OCD showed a significantly higher age at onset compared to the other group (29.4±15.1 years vs 18.7±9.2 years ;p<.001). Consistently, in the G-OCD group, adult onset (≥ 18 years) resulted significantly more represented (75% vs 41.1%, p<.001). Cognitive behavioural therapy (CBT) was less frequently utilized in the G-OCD group compared to the group with age < 65 years (20.8% vs 41.8%, p<.05). Female gender was more represented in the G-OCD group, though not reaching a statistically significant level (75% vs 56.4%, p=.07). When the whole sample was divided on the basis of the median age (age < 42 years vs age ≥ 42 years; n=213 (51.2%) vs n=203(48.8%)), the group with age ≥ 42 years showed significantly higher age at onset and rate of adult onset (respectively 23.01±11.7 years vs 15.7±6.1 years, 75% vs 41.1%; p<.001). Female gender was significantly more represented in the group with age ≥ 42 years (52.1% vs 63.1%, p<.05). Conclusions The present international multicenter study revealed a significantly lower rate of patients with age ≥ 65 years compared to patients younger than 65 years. Patients with G-OCD showed a significantly higher age at onset and rate of adult onset compared to non-geriatric patients. Moreover, in G-OCD patients CBT was less frequently utilized. Subgroups divided on the basis of the median age of the sample showed that the age ≥ 42 years group had a significantly later onset of illness and higher rate of adult onset and female gender.