Objectives: Mental illnesses are common among outpatient clinics, but only some of these patients receive adequate treatments and attend. The purpose of this study is to evaluate the dropout rate and identify the predictors of dropouts in outpatient clinics in Roozbeh Psychiatric Hospital.

Methods: A questionnaire designed by expert psychiatrists was filled. The questionnaire consists of information collected from medical records of 400 patients who consulted outpatient clinics of Roozbeh Psychiatric Hospital. The data were analyzed using SPSS16.

Results: The total dropout rate was 57.8% (males: 33.5% and females: 24.3%). The dropout rates in adult and child and adolescent clinics were 58% and 43.8%, respectively. A total of 11% of total dropout rate was in patients under 18 years, 41.8% was in patients aged 18 to 65 years, and 5% was in patients aged 65 years and over. There were  significant relationships between drop out rate and variables of patients' age, educational degrees, occupation, referral point, and type of diagnosis. However, no significant relationships were found between drop out rate and gender or marital status of the patients.

Conclusions: Dropout is a common barrier in delivering outpatient psychiatric treatments. There need to be proper interventions to reduce such dropouts.