Objective: There is a growing body of evidence support- ing the involvement of circadian rhythm abnormalities in the psychopathology of obsessive-compulsive disorder. However, the effects of chronotype preference on the clinical features of this disorder are elusive. The aim of this study is to investigate how chronobiological predis- positions of people with obsessive compulsive disorder affect obsessive compulsive disorder symptomatology, age of onset, course of the disease and accompanying comorbid conditions. Method: Within this cross-section- al study, 76 participants with mean age of 32.53, who have been under treatment with a diagnosis of obses- sive-compulsive disorder, were evaluated. Sociodemographic and clinical data form, Yale-Brown Obsessive Compulsive Scale, Morningness and Eveningness Questionnaire, Hamilton Depression Rating Scale, and Hamilton Anxiety Scale were applied to the participants. Results: 65.8% (n=50) of the participants consisted of women. Mean age of onset is 18.74 ± 9.36 years. Most of the patients were reactive type (n=47, 61,8 %). Most common obsession type was contamina- tion (n=53, %69,74), the most common compulsion type was cleaning/washing (n=52, %68,42). There was no significant correlation between morningness and eveningness scale scores and obsession and compulsion types. No significant correlation was found between morningness and eveningness scale scores and OCD onset age. There was no significant difference between morningness and eveningness scale scores according to the OCD type of the patients and the presence of accom- panying clinical diagnoses. Discussion: Morningness or eveningness chronotype tendencies did not have a sig- nificant impact on the clinical appearance of OCD.