A worldwide survey of nonmedical drug use among U.S. military personnel was conducted in 1980. A stratified multistage probability sample was drawn and a questionnaire administered by staff of Burt Associates, Inc. The results show that 27% of the military personnel reported they had used some type of drug or drugs non-medically in the past 30 d; 36% reported such use within the past year. Prevalence rates are presented for each of nine drug categories. Nonmedical drug use is limited primarily to junior enlisted personnel. The overwhelming majority of nonmedical drug use in the military is occasional or experimental in nature. From these results obtained, it is estimated that 3% of Department of Defense (DOD) junior enlisted personnel were physiologically drug dependent and a total of 4% were physiologically or psychologically drug dependent at some time during the preceding 12 months. The proportions of junior enlisted personel reporting consequences of drug use and work impairment because of drug use are also presented. There is no general pattern of nonmedical use being more prevalent among military personnel than comparable civilians.