This study was undertaken to determine the prevalence of HBsAg among drug-dependent patients in Jeddah, Saudi Arabia. Over a period of 10 months, 1498 patients admitted for drug dependence were tested for HBsAg. For each patient, the age and route of drug abuse were recorded. All the HBsAg positive patients were further tested for HBeAg and anti-Hbe. 244 patients were positive in HBsAg, giving a prevalence of 16.3%. Considered separately, the prevalence of HBsAg among drug users and non-intravenous drug users were 18.5% and 6.7% respectively. 225 (92.2%) of the 244 HBsAg positive patients were intravenous drug users. Of the 244 HBsAg positive patients, 35 (14.4%) were positive for HBeAg. The persistence for years of HBeAg in chronic HBsAg carriers may cause chronic liver disease and primary liver carcinoma. There is a need for more public education on this condition in order to control its spread and to prevent future complications.