The prevalence of zopiclone misuse in clients attending a methadone maintenance programme in Dublin through detection of its degradation product, 2-amino-5-chloropyridine (ACP) on urinalysis is outlined. Urine samples from all 158 clients were tested for the presence of ACP, opiates, benzodiazepines, cocaine, alcohol and cannabis. Of the 37 (23%) clients who tested positive for ACP, 23 (62%) were interviewed. A profile of zopiclone misusers is outlined, including details of demographics, drug history, viral status, recent urinalysis results and opinions on zopiclone. Of the 14 (38%) clients who were not interviewed, information was obtained from their clinical casenotes and documented urinalysis results. The prevalence of zopiclone misuse was reported as 23%. Benzodiazepines were the most popular drug of misuse with zopiclone followed by heroin/opiates. Zopiclone is being misused by drug users in Dublin in the context of many other drugs. Prescribing of zopiclone should be restricted, especially among drug misusers.