OBJECTIVES: The aim of this study was to explore patients’ general and specific beliefs about medicines among depressed patients and effect on adherence and other clinical outcome in Saudi Arabia. METHODS: a cross-sectional design used to measure patients’ general and specific beliefs among depressed patients, using BMQ general and specific scales. Patients were recruit from outpatient clinic at AL-Amal hospital in Riyadh (psychiatric hospital). 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 patients report low adherence to antidepressant medication. Both low and high adherence group scored high in the necessity beliefs (18.02 (SD 3.91)-18.32 (SD3.9)respectively with no statistically different. contrariwise patients with high adherence had significantly lower level of concerns belief about antidepressants medication and less harmful belief also the same finding with general overuse belief. CONCLUSIONS: General patients beliefs either general overuse or general harm about medication influence patients taking medication behavior and have negative correlation with adherence to medication on other hand only specific concerns belief to antidepressant have a positive correlation with adherence to antidepressant this finding will help psychiatric to improve adherence and clinical outcome by addressing medications taking behavior using a systematic approach based in this finding.