Abstract: Objective This study was conducted to explore convenient and feasible and effective methods for estimating the size of drug users. Methods The size of the present drug users was estimated by methods of capture-recaptuer and multiplier.The data of drug users was from Compulsory Detoxification Institute, Voluntory Detoxification Center and Methadone Clinics in Wenzhou. Results The estimated population of drug users by method of capture-recaptuer was 18 901 in Wenzhou and 11 248 in Lucheng, which were 1.96 and 1.66 times respectively of registrated numbers.While by multiplier method,the size of drug users was 20 016 in Wenzhou and 13 953 in Lucheng,which were 2.08 and 2.06 times of registrated numbers respectively.The two methods were well consistent. Conclusions The application of capture-recaptuer method of estimating the size of drug users, which had the merits of easy handling and low cost, made it possible not to contact them directly and so the results were more reliable.While adoptting multiplier method, it was better to select Detoxification Institute as contact target, Voluntory Detoxification center and Methadone Clinic as source of abtaining multiplier.