Data pertaining to prevalence and frequency of drug use were obtained from 1,394 Western Australian metropolitan high school students using a self-report questionnaire. Alcohol, marijuana, tobacco, hallucinogens, and amphetamines were reported as the most prevalent substances, with over 50% of ''current drug users'' using alcohol and marijuana on a frequent basis (i.e., weekly to more than once per day). Significant interactions existed between Gender and prevalence of tobacco and hallucinogens; and School Year Level and prevalence of tobacco, alcohol, hallucinogens and amphetamines. In terms of the frequency of use, significant interactions were found between Gender and marijuana; and between School Year Level and tobacco. Approximately 40% of substance-using participants used one single substance, 40% used two or three substances, and 20% used four or more substances. The results suggest there is a need for educators to have a greater understanding of the patterns of substance use in order for them to more aptly shape drug education programs. (C) 1997 Elsevier Science Ltd.