Ruminative thinking, the tendency to dwell on particular ideas or themes, can be a prominent part of the phenomenology of major depression, but it rarely has been the focus of empirical research. We attempted to replicate (in adult psychiatric inpatients age > or = 50 years with DSM-III-R major depression) the previously published finding that ruminative thinking was associated with melancholia and with psychosis. In our sample, these associations were not present. In addition, we explored the relationships of ruminative thinking to specific areas of thought content (e.g., suicidal ideation, somatic worry), cognitive function and overall functional status; ruminative thinking was not associated with suicidal ideation, but was associated with greater somatic worry and with poorer functional status, although these associations were not independent of overall depressive severity. A substantial proportion of subjects were unable to complete the cognitive measures; ruminative thinking was independently associated with inability to complete these tasks. We conclude that ruminative thinking is a meaningful and common clinical phenomenon among severely depressed older inpatients. Further investigations in inpatients and other populations examining its relationships to other phenomenology, to course and outcome, and to putative underlying mechanisms of depression are warranted.