Some HIV-infected injecting drug users (IDUs) on drug abuse maintenance treatment have access to highly active antiretroviral therapy (HAART); this raises questions about the effects of individual treatments on the efficacy of HAART. The French Cohort Study of HIV-infected IDUs - MANIF-2000 - allowed one to assess whether buprenorphine differentially impacts efficacy of HAART. Of the 103 HAART-treated patients, (excluding active IDUs and patients on methadone), 20 were on buprenorphine substitution treatment and 83 were ex-IDUs. A linear regression model used the differences in viral load titre before and after treatment initiation, as a dependent variable, and showed that buprenorphine treatment was not significantly associated with viral load trend. This was also the case when adjusting for other potential confounders, and suggests that there is no major short-term influence of buprenorphine on HIV viral load in HAART-treated patients.