Objective: This study aimed to explore the current patterns of psychiatric diagnoses in inpatient and outpatient psychiatric settings in Saudi Arabia. Methods: Cross-sectional study was conducted on patients seeking psychiatric advice at six hospitals in the five main regions of Saudi Arabia. The data were primarily obtained by reviewing patient charts. Results: Total of 1,205 patients were recruited. The majority was unemployed (71.4%), had a low level of education (85.5%), and had low income (61.9%). The most common psychiatric diagnoses among inpatients were schizophrenia (55.8%), bipolar disorder (23.3%) and major depressive disorder (7.2%). The most common psychiatric diagnoses among outpatients were major depressive disorder (29.3%), schizophrenia (28.9%), generalized anxiety disorder (15.6%) and bipolar disorder (11.5%). Primary psychotic disorders and secondary psychiatric disorders were significantly more frequent among men whereas primary bipolar disorders and depressive disorders were significantly more frequent among women in both inpatient and outpatient settings. Psychotic and bipolar disorders were significantly more frequent among younger patients whereas depressive disorders were significantly more frequent among older patients; anxiety disorders were of similar frequency in all age groups. Discussion: The most common psychiatric diagnoses among inpatients were schizophrenia and bipolar disorder whereas the most common psychiatric diagnoses among outpatients were major depressive disorder and schizophrenia.