Occurrence and features of depression were studied in 150 medical in-patients. At initial interview within a week of admission a total of 24 per cent met a criterion for depression based on the Beck Depression Inventory. Although they showed the usual clinical features, few were recognized or referred to psychiatrists. Depression was commoner in those with more severe medical illness, more concomitant stress, and more previous depressions. In most cases the occurrence and course appeared closely bound up with the medical illness. When comparisons were made with depressives in psychiatric treatment, the medical depressives were less severely depressed. With severity equated, medical depressives more often showed feelings of pessimism, helplessness, anxiety and self pity, but less often suicidal feelings. In general their state appeared more appropriate to the life situation, suggesting some characteristics of a borderline between normal and pathological depressed mood.