The perceived impact of life events on drug use was tested and specifically the hypothesis that drug use is a response to stress. Three groups of drug users were examined: heroin users, heavy drinkers and smokers. These were compared to non-drug using controls and the frequency of life events in the lives of each group was recorded. Whereas both the heroin and alcohol groups reported more stressful life events in their lives, no such difference was found for the smokers when compared to their control group. However, the differences between the heroin users and their control group on the one hand, and between the drinkers and their control group on the other, were found to consist largely of events which were consequences of the drug use itself. Furthermore, these two drug user groups (alcohol and heroin respectively) apparently experienced less stressful events than their control groups when events unconnected with drug use were examined alone. Nonetheless, this is interpreted as due to the way these groups perceive events rather than as an accurate record of their experiences. The conclusion is that heroin and alcohol use act as stress 'buffers', in that they reduce awareness of ongoing stressful life events. But in so doing they introduce a lot of new stresses which possibly maintain the drug use and therefore ultimately increase stress.