Objective: To evaluate trends in psychiatric bed occupancy by elderly inpatients in the Brazilian public health care system between 2000 and 2010 and to determine the leading psychiatric diagnosis for hospital admissions. Methods: Data from all 895,476 elderly psychiatric admissions recorded in the Brazilian Public Health Care Database (DATASUS) between January 2000 and February 2010 were analyzed. Polynomial regression models with estimated curve models were used to determine the trends. The number of inpatient days was calculated for the overall psychiatric admissions and according to specific diagnoses. Results: A moderate decreasing trend (p < 0.001) in the number of inpatient days was observed in all geriatric psychiatric admissions (R2 = 0.768) and in admissions for organic mental disorders (R2 = 0.823), disorders due to psychoactive substance use (R2 = 0.767), schizophrenia (R2 = 0.680), and other diagnoses (R2 = 0.770), but not for mood disorders (R2 = 0.472). Most admissions (60 to 65%) were due to schizophrenia. Conclusion: There was a decreasing trend in inpatient days for elderly psychiatric patients between 2000 and 2010. The highest bed occupancy was due to schizophrenia, schizotypal, and delusional disorders.