This report summarizes present scientific knowledge concerning the connection between marijuana use and health. It describes the subjective and physiologic effects of short-term use, including changes in intellectual and motor performance and acute psychotic episodes. While few data exist to prove the harmful effect of long-term use, there is increasing evidence that frequent, heavy use is correlated with a loss of interest in conventional goals and with development of lethargy. The need for more research in both physiological and psychosocial areas is stressed.Abstract Teaser