A qualitative screening technique was developed for the detection of 2-amino-5-chloropyridine, a newly identified decomposition product of zopiclone and metabolites after alkaline hydrolysis of urine samples. The method was elaborated using a standard operation procedure (Merck Tox Screening System), combining a solid-phase extraction with reversed-phase high-performance liquid chromatography and diode array detection. The limit of detection, expressed as zopiclone concentrations in spiked urine, was found to be 0.5 microg/mL. Field urine samples from a volunteer were positive for 2-amino-5-chloropyridine until 16 h after ingestion of one therapeutic dose of Imovane (7.5 mg zopiclone).