To investigate potential delays in endogenous melatonin in individuals with obsessive-compulsive disorder (OCD). First, data are presented for 15 individuals with OCD and matched healthy controls. Next, nine additional participants with OCD who did not have matched controls were added, resulting in a sample of 24 individuals with OCD. All participants were assessed for sleep and circadian rhythm disturbance. Dim light melatonin onset (DLMO) was derived from salivary melatonin and was used in conjunction with sleep diaries, interview measures, and questionnaires. A subset of the OCD group (n = 16) also used actigraphy. In sum, 42% percent (10/24) of the patients with OCD met the criteria for delayed sleep-wake phase disorder (DSWPD) in comparison to 0% in the control sample. DLMO was significantly later in individuals with OCD compared to controls. DLMO and bedtime were not significantly associated with the severity of obsessive-compulsive symptoms or negative affect. Replication of the findings presented herein, particularly the DLMO results, is warranted. Further, there are now three studies showing that nearly ½ of individuals with OCD meet criteria for a DSWPD. Future studies can explore the mechanisms underlying these connections and the implications of this comorbidity. These findings may increase our understanding of OCD and inform future interventions. Significant Outcomes:•Over 1/3 of individuals with OCD met criteria for delayed sleep-wake phase disorder (DSWPD)•Individuals with OCD have significantly later DLMO compared to matched controls•DLMO was not significantly correlated with OCD severity. Limitations:•This study has a modest sample size•This study is limited in the amount of information regarding the implications of the delayed bedtimes and dim light melatonin onset for individuals with OCD.