In 1971 and 1975, the Committee on Drugs provided information about marijuana for the Academy membership.1,2 Since that time, marijuana use by children and adolescents has continued to increase. Investigations of the biologic effects of the agent have expanded, and there is justification for concern about frequent, chronic use by youth. In addition, marijuana use and experimentation with other drugs are now being promoted to children in subtle and insidious ways which need to be identified (Figs 1 to 5). Pediatricians should be aware of the changing pattern of marijuana use in this country. Whereas occasional use by an adult may have little health consequence for the individual, frequent use by large numbers of children and adolescents raises different concerns. The National Institute on Drug Abuse (NIDA) conducts annual surveys of marijuana use in this country and reported in a recent publication3 that 10% of all high school seniors smoke marijuana daily. In the 12- to 17-year old group, 16% of those surveyed in 1977 used marijuana in the month preceding the survey. Even if the incidence figures are not entirely accurate, an increase in use by these two groups from 1976 to 1977, as determined by similar annual sampling techniques, is clear. Nationwide data since 1977 are not yet available, but in two states surveyed in 1978, 16% of high school seniors smoked marijuana daily (R. C. Peterson, PhD, personal communication, 1979). This information supports the conclusion that use in youth had increased each year since 1975. Extrapolation of additional data collected by NIDA revealed that in 1977 about 16 million Americans were current users of marijuana (ie, used the drug during the month preceding the survey).3