AIMS: To verify the profile of the elderly and their main diagnoses in the geriatrics psychiatric outpatient clinic and the psychiatric hospitalization unit of a tertiary hospital. METHODS: A cross-sectional study of population-based was performed in a tertiary referral hospital, with individuals aged ≥55 years attending the geriatric psychiatric outpatient clinic and psychiatric hospitalization, from 2014 to 2018. Data were collected through interviews. The studied variables were sociodemographic and clinical aspects.  RESULTS: A total of 497 individuals were evaluated, 269 from the psychiatric outpatient clinic and 228 from the psychiatric hospital. The mean age was 69.34±8.87 years. Most of the patients were female (75.8%), had no partner (56.3%), had primary education (50.3%), lived in Porto Alegre (75.6%) and were retired (66.5%). According to the clinical variables studied, 89.6% of the individuals had some morbidity, 36.9% had already been admitted to the psychiatric ward, the most common diagnosis was depression (40.8%), followed by bipolar disorder (19%) and anxiety (14.1%). CONCLUSIONS: With the population aging, it is expected to increase morbidity and mental disorders, requiring more specific diagnostic tools and better treatment approaches. There are still no consistent data on the management of mood disorders in the elderly, so our study can guide a better care for elderly and aging individuals, improving the planning of health services and policies.