To estimate the point-prevalence of major depression in elderly medical inpatients according to a computerized diagnostic system, a two-phase design was carried out. A consecutive series of 198 elderly medical inpatients completed two self-rating scales for depression (Beck Depression Inventory, Geriatric Depression Scale) and the Mini-Mental State Examination. According to these screening instruments, 69 'probable cases' were identified and were referred for psychiatric evaluation using the Geriatric Mental State Schedule. Only 10 patients were identified as diagnostic cases of depression according to the GMS-AGECAT package. The estimated prevalence rate for depression according to AGECAT in this population was 5.9% (95% confidence limits 2.3-9.3%). This is lower than has been found in previous studies in elderly medical inpatients. Possible reasons for this finding are discussed.