BACKGROUND The purpose of this study is to investigate the prevalence and the clinical features of night eating syndrome (NES) in patients with depression and anxiety disorders. METHODS The study was conducted at Bakırköy State Hospital for Mental Health and Neurological Disorders. Three-hundred out-patients who had major depression (MD), panic disorders (PD), general anxiety disorders (GAD) and obsessive-compulsive disorders (OCD) participated in the study. The semi-structured socio-demographic form, the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I), Night Eating Questionnaire, and NES Evaluation Questionnaire were implemented. RESULTS In our sample, the prevalence of the NES was 15.7% (n=47). NES frequency was significantly higher in the patients diagnosed with major depression (MD 22%, GAD 7.8%, OCD 12.5%, PD 14%). Smoking, presence of past suicide attempts, rates of antipsychotic drugs use, and average scores of body mass index (BMI) were significantly higher in the patients who had NES. In this sample, depression, BMI, and smoking were found to be determinants of NES. CONCLUSIONS This study shows that NES may be frequently observed in patients admitted to psychiatric clinics, especially in those with major depression. Evaluation of NES in psychiatric patients may help the treatment of the primary psychopathology and prevent the adverse effects, like weight gain, which may reduce the quality of life.