Tenofovir disoproxil fumarate (TDF) has shown in vitro activity against both HIV and hepatitis B virus (HBV). We retrospectively evaluated the efficacy of TDF (300 mg/d), administered as a part of anti-retroviral therapy, in a large cohort of HIV/HBV-coinfected patients. Sixty-five HIV/HBV-coinfected patients who received TDF for at least 6 months with serum HBV DNA levels above 2.3 log10 copies/mL at TDF initiation and who had stored serum samples before and during TDF therapy were included. Serum HBV DNA was measured on stored samples. The median follow-up period was 12 (Q1-Q3: 8-17) months. Serum hepatitis B e antigen (HBeAg) was positive in 54 patients (83.1%). Fifty-two patients (80.0%) were receiving lamivudine (LAM) (150 mg twice a day), and 68.8% had documented LAM resistance at baseline. Among HBeAg-positive patients, the median reduction from baseline (8.17; Q1-Q3 = 7.30-8.30 log10 copies/mL) of serum HBV DNA was 4.56 log10 copies/mL (Q1-Q3 = 3.33-5.55) (P < .0001). In HBeAg-negative patients, serum HBV DNA decline from baseline (4.83; Q1-Q3 = 2.69-6.40 log10 copies/mL) was 2.53 log10 copies/mL (Q1-Q3 = 0.39-4.10). At the end of the study, HBV DNA became undetectable in 29.6% and 81.6% of the HBeAg-positive and HBeAg-negative patients, respectively. Serum HBeAg became negative in 4 patients, 2 of whom acquired serum hepatitis B e antibody. In conclusion, this retrospective analysis demonstrates the efficacy of TDF against wild-type, presumed precore mutants and LAM-resistant HBV when used as a part of anti-retroviral therapy in HIV-coinfected patients.