This paper describes the epidemiology of drug overdose deaths investigated by the medical examiner in one of the cities participating in the Canadian Community Epidemiology Network on Drug Use and assesses the quality of the information obtained from medical examiner charts with respect to drug overdose deaths, for surveillance purposes. Information was abstracted from medical examiner charts of all deaths involving drugs from 1993 to 1995 in Halifax, Nova Scotia. During these three years, 636 deaths from all causes were investigated by the medical examiner. Of the 42 overdose deaths, 47.6% were suicides. Ethanol was detected in 47.8% of overdose deaths, and 61.9% of all overdose deaths involved psychotropic medications. Two deaths were attributed to an illicit drug (cocaine). An independent review performed by a toxicologist and a medical examiner revealed poor overall agreement concerning overdose as a cause of death (Kappa coefficient: 0.27). In conclusion, the average crude mortality rate due to drug overdose in Halifax from 1993 to 1995 was 4.1 deaths per 100,000 population. Potential threats to the quality of data were the lack of standardization concerning toxicological testing and the definition of drug overdose.