The Minnesota Multiphasic Personality Inventory (MMPI) was administered to 210 young people who either used no drugs, used non-opioids, used opioids but did not inject and drug injectors. From the data collected a short scale of 37 items was derived which distinguished between non-users and drug users. Validation was then attempted using 214 subjects who were either in drug treatment programmes or alcohol treatment programmes as well as appropriate control groups. The Drug Misuse Scale was able to distinguish between these groups. The MacAndrew Scale proved better at distinguishing subjects in alcohol treatment programmes. However, the Drug Misuse Scale proved to be significantly better at distinguishing the drug misusers. It is suggested that the Drug Misuse Scale may prove a valuable clinical tool.