Only four (1 percent) cited cocaine abuse as the main drug problem. Heroin was the most common main drug. Detailed information was available on 355 of these subjects. During the study period 63 patients reported using cocaine and the proportion of subjects using cocaine increased from 13 percent to 29 percent. Within the sub-group of cocaine users, there was a marked increase in the use of smokable forms of cocaine from 15 percent in 1987 to 75 percent in 1989. In view of the increased dependence risk associated with smoking cocaine, this is seen as an ominous development. Figure and 11 references. (Author abstract)