OBJECTIVE To describe the prevalence of and characteristics associated with major and minor depression in older medical inpatients and to compare associated characteristics by sex and history of depression. METHODS Cross-sectional study of two patient samples, with and without a screening diagnosis of major or minor depression. METHODS The medical services of two acute care hospitals. METHODS Medical admissions of people aged 65 and older with at most mild cognitive impairment (N=380). METHODS Diagnoses of major and minor depression (Diagnostic Interview Schedule), cognitive impairment (Mini-Mental State Examination), premorbid disability, sociodemographic variables (including social networks and support), comorbidity, severity of illness, history of depression. RESULTS The prevalence of major depression differed by hospital, ranging from 14.2% (95% confidence interval (CI)=11.7-17.1) in Hospital A to 44.5% (95% CI=33.1-56.4) in Hospital B. The prevalence of minor depression was similar in the two hospitals, ranging from 9.4% (95% CI=7.4-11.9) in Hospital A to 7.9% (95% CI=2.9-16.3) in Hospital B. After adjustment for hospital, the same characteristics (history of depression, premorbid disability, cognitive impairment, perceived adequacy of support, and visits from friends) were associated with major and minor depression, although most of these associations tended to be weaker for minor depression. Most of these factors were also associated with depression in multivariate analyses. The most important characteristics in women were premorbid disability, history of depression, and adequacy of emotional support; in men they were history of depression, cognitive impairment, and adequacy of emotional support. A cerebrovascular or other cardiovascular diagnosis did not explain the association between depression and cognitive impairment. CONCLUSIONS Major and minor depression occur frequently in older medical inpatients and are associated with similar patient characteristics. A history of depression and the patient's sex should be considered in the identification and interpretation of these associated factors.