Objectives: To measure the prevalence of sexual dysfunction in psychiatric outpatients treated with fluoxetine, paroxetine, venlafaxine or mirtazapine. Methods: This is a retrospective cross-sectional study conducted in Sultan Qaboos University Hospital, Muscat, Oman. All patients above 18 years of age, attending psychiatric clinic and taking fluoxetine, paroxetiene, venlafaxine or mirtazapine for various indications were invited to participate in the study. A data collection sheet was designed to document the patients’ demographic features, psychiatric diagnosis, type, dose and duration of antidepressant treatment. Sexual side effects’ part of Toronto Side Effect Scale (TSES) was used to assess the presence of sexual dysfunction. Results: A total of 137 patients (Male: 51%, Female: 49%) were included in the study. The mean age for the participants was 38 years (range: 19-72 years).The number of patients for each antidepressant was as follows: Paroxetine (52 patients), fluoxetine (36), mirtazapine (36 patients) and venlafaxine (17 patients). The average duration of the antidepressant use was 3.9 years. The overall prevalence of sexual dysfunction was 39%. Paroxetine was the most common antidepressant associated with sexual dysfunction especially for decreased libido (59.6%) and delayed ejaculation (34.4%). In contrary, mirtazapine was the lowest among antidepressants to cause sexual dysfunction. Conclusion: Sexual dysfunction is common among patients treated with antidepressants particularly selective serotonin reuptake inhibitors (SSRIs).Addressing this side effects early in treatment can improve compliance to treatment and prevent relapse.