OBJECTIVES: :The aim of this study was to explore patients’ adherence to antidepressant medication and predictors are associated with adherence, among patients diagnosed with depression in a psychiatric hospital in Riyadh , Saudi Arabia. METHODS: Non experimental cross-sectional design used to measure adherence to antidepressants among depressed patients and predictors are associated with adherence, patients were recruit from outpatient clinic at AL-Amal hospital in Riyadh (psychiatric hospital) between August 2013 and January 2014. RESULTS: :A total of 403 patients meet the inclusion criteria and were participated in this study. Two hundred three representing 50.37 % of the total study sample, were female, while the remaining 200 (49.6 %) were male, with average 39 years. 52.9% of the patients report low adherence to antidepressant medication with a statically significant different between low adherence and high adherence scour in female gender, younger age, patients with shorter duration of illness and have lees number of visit to outpatient clinic. CONCLUSIONS: :Low adherence is a common health problem among depressed patients in Saudi Arabia, this study has improve understanding of adherence predictors to antidepressant and their association, this understanding should help care giver and stakeholder to improve depressed patient management and clinical outcome by addressing medications taking behavior using a systematic approach based in this finding.