Introduction: Comorbid obsessive-compulsive disorder (OCD) has been reported among patients with schizophrenia in other countries. But, the literature is not well-documented on this issue in Iran (Persia). The present study aimed to investigate the prevalence and severity of OCD and some of its related factors in a group of patients with schizophrenia in Iran. 
Methods: This is a cross-sectional study. A total of 150 hospitalized patients with schizophrenia were recruited at Razi Psychiatric Hospital in Tehran, Iran. Demographic and clinical checklists, as well as the Yale-Brown obsessive-compulsive scale (Y-BOCS), scale for assessment of negative symptoms (SANS), and scale for assessment of positive symptoms (SAPS) were administered to collect data. OCD was the dependent variable and independent variables included age, sex, severity of positive and negative symptoms, duration of schizophrenic disorder, the number of hospitalizations, and antipsychotic medications administered to them. Data were analyzed by analysis of variance (ANOVA), Chi-square, and T-test. 
Results: Overall, 31.3% of patients had OCD with an average severity of 12.81(SD=10.27). The prevalence of OCD was not affected by the number of psychiatric hospitalizations for schizophrenia or the duration of schizophrenic disorder. The severity of OCD significantly reduced as the duration of schizophrenia and the severity of negative symptoms increased. 
Conclusion: OCD was found among a considerable proportion of the study sample. OCD may be associated with exacerbating schizophrenic symptoms. Therefore, psychiatrists should consider the simultaneous treatment of OCD and schizophrenia. Further studies are suggested in this issue.

Introduction: Obsessive–Compulsive Disorder (OCD) is a complex and heterogeneous neuropsychiatric syndrome. Contamination obsessions and washing/cleaning compulsions are the most frequent clinical OCD subtypes. The current study aimed at examining the neuropsychological impairments in drug-naive obsessive-compulsive (OC) washers without depressive symptoms and their association with the severity of symptoms.
Methods: In the current causal-comparative study, 35 patients with diagnostic and statistical mental disorders class (DSM)-IV diagnosed with washing-subtype OCD and 35 healthy subjects were selected by the convenience sampling method and evaluated by computerized neuropsychology battery and clinical tests as Stroop Color-Word Test (SCWT), Wisconsin Card Sorting Test (WCST), Go/No-Go Test, Digits Forward (DF), Digits Backward (DB), Yale-Brown Obsessive–Compulsive Scale (Y-BOCS), Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), and General Health Questionnaire (GHQ)-28. The patients were matched to the comparison group with regard to age, gender, intelligence quotient (IQ), education, and handedness. All the tests were standardized in Iran. SPSS version 20.00 was used for descriptive and analytical data analysis.
Results: There was no statistically significant different between the OCD washing and the control groups regarding socio-demographic variables or IQ. There were significant differences between the OC washer and the healthy control groups on the neuropsychological functioning. The obtained results suggested that OC washers performed significantly worse on neuropsychological measures than the controls. There was no significant association between the severity of OC symptoms and the neuropsychological functions in the OCD washing group.
Conclusion: It was concluded that executive function impairment, which is a core feature in OC washers was trait-like in nature.