The authors studied a group of 149 hospitalized cocaine abusers as a follow-up to previous research performed in 1980-82, which had revealed a high prevalence of affective disorder in cocaine abusers. The authors hypothesized that the changing epidemiology of cocaine abuse since that time may have been accompanied by changes in the characteristics of patients seeking treatment for dependence on the drug. The cocaine abusers were compared with 293 other drug abusers to see whether clinical changes over time were specific to individuals abusing cocaine. The authors found slightly more affective disorder in the cocaine abusers when compared with the other patients (26.8% vs. 20.1%), with a significantly higher rate of cyclothymic disorder (11.4% vs. 2.7%, p less than .001). Affective illness was significantly more prevalent in the first-degree relatives of the cocaine abusers when compared with the sex-matched relatives of the other patients (p less than .05). Diagnostic trends changed a great deal, however, between the original 1980-82 study sample and the follow-up 1982-86 sample. The rate of affective disorder decreased over time from 50.0% to 21.0% (p less than .01), and the rate of affective illness in the families also declined, from 31.0% to 11.5% in females (p less than .001) and from 14.3% to 2.2% in males (p less than .001). No such change occurred in the comparison group of opioid and central nervous system depressant abusers. The authors conclude that although a substantial number of cocaine abusers suffer from concurrent affective disorder, this form of premorbid psychopathology has become a less important risk factor for the development of chronic cocaine abuse as cocaine use has become more widespread.