This study explored patterns of ecstasy use and associated harm through the administration of a structured interview schedule to 329 ecstasy users, recruited from three Australian cities. A broad range of ecstasy users were interviewed, but on the whole, the sample was young, relatively well educated and most were employed or students. Patterns of use were varied, although extensive polydrug use was the norm. High rates of intravenous drug use were recorded, which may relate to an over-representation of chaotic intravenous polydrug users. Subjects had experienced an average of eight physical and four psychological side-effects, which they attributed to their ecstasy use in the preceding 6 months. Approximately 40% of the sample also reported financial, relationship and occupational problems. Young, female, polydrug users and those who binged on ecstasy for 48 h or more appeared most at risk of experiencing harm that they related to their ecstasy use. One-fifth of the sample had received treatment for an ecstasy-related problem, most often from a GP or natural therapist, and 7% were currently in treatment. One quarter wanted to reduce their use because of financial, relationship and psychological problems. A total of 15% wanted formal treatment for an ecstasy-related problem and 85% requested more information. These results have implications for the development of policies to respond to drug use among this population. Copyright (C) 1999 Elsevier Science Ireland Ltd.