In a community study of 1173 very elderly (> or = 77 years) subjects, a screening interview was followed by a CAMDEX diagnostic interview in a subsample of 461. The estimated prevalence of DSM-III-R major depressive disorder in the community sampled was 2.4% (95% CI 0.9%, 4.0%). Using CAMDEX criteria, the prevalence of depressive illness was 3.0% (95% CI 0.7%, 5.3%). 10% of those who had a diagnostic interview were rated as having depressive symptoms of mild or moderate severity. Of these, approximately 1/3 met diagnostic criteria for major depressive disorder. The significance of these findings and the possible need for wider criteria for depression in the elderly are discussed.