The addition of corticosteroids in the early 1950s to the treatment armamentarium provided cure of some diseases and control of many. They have become an integral part of many cancer treatment regimens. Early reports of severe affective disorders appear less frequent today in patients receiving steroids, though controlled studies are rare. Minor mood changes are common, ranging from the euphoria of initial treatment to depressive symptoms on withdrawal. The most common severe disturbances seen clinically in cancer patients are the organic mood disorders and delirium. Studies are needed, especially in cancer, which control for prior psychiatric history, cancer site, cancer treatment, pain regimen, coexisting cancer complications, especially central nervous system complications, and physical performance status. DSM-III-R terminology must be used as the diagnostic classification for reliable investigation. A more careful clinical delineation of the mental changes with steroids is desirable not only for the clinical relevance, but for the potential understanding of the etiology of mood disorders and mental changes seen in delirium.