Immunomodulatory agents for the treatment of certain oncologic disorders are rapidly moving from the research laboratory into clinical practice. These agents may not be void of potential neuropsychiatric sequelae. The following clinical report concerns a previously nondepressed patient with no history of psychiatric disorders who became depressed and killed himself while being treated with interleukin-2. It is important that consulting psychiatrists be sensitive to acute emotional changes in cancer patients taking immunomodulatory agents.