摘要To evaluate the reliability and validity of the Chinese version of addiction severity index (ASl)-5th version (ASI-C-5), in illegal drug users receiving methadone maintenance treatment (MMT) in China. Methods One hundred and eighty-six heroin addicts (144 men and 42 women) receiving MMT at three clinics in Guizhou province, southwest China, were recruited. They were all interviewed with a questionnaire of ASI-C-5 and 35 were re-interviewed at an interval of seven days to assess its test-retest reliability. Results Cronbach's alpha for internal consistency of CSs varied from 0.60 to 0.81 in all domains. Test-retest reliability of composite scores (CSs) of ASI-C-5 were satisfactory (r=0.38-0.97). Based on item analysis and expert's suggestions, five items were deleted and one item was modified in ASI-C-5. Criterion validity of ASI-C-5 was found acceptable, as compared to addicts' self-rating anxiety scale (SAS) and self-rating depression scale (SDS) (r=0.59 and 0.45) except for social support rating scale (SSRS). Conclusions ASI-C-5 can be used for heroin addicts receiving MMT with acceptable reliability and validity.