OBJECTIVE: The authors had for aim to describe the effectiveness and the safety of a saquinavir/ritonavir (SQV/r) regimen, 1000/100mg twice daily, in HIV-infected pregnant patients. PATIENTS AND METHOD: We made a prospective and observational study of HIV positive female patients beginning or going on SQV/r antiretroviral treatment (ART) during pregnancy. RESULTS: Sixty-two patients were enrolled from July 2007 to June 2009 in 10 infectious diseases units in France. Thirty-six women (group 1) were ART naive on inclusion, 20 (group 2) had been previously treated and then switched to SQV/r, six (group 3) were treated with SQV/r before pregnancy. 58 patients delivered while on SQV/r regimen after a median pregnancy duration of 39 WA. Eighty percent had a viral load below 50 copies/mL and 93% below 400 copies/mL: respectively 77% and 93.5% in group 1, 83% and 89% in group 2, 83% and 100% in group 3. The median SQV minimum concentrations (C(min)) measured at the third trimester and at delivery were adequate, respectively 0.91 mg/L and 0.86 mg/L. Most women (52%) had a vaginal delivery; 12 (21%) had an elective caesarean section, for obstetrics factors in eight cases. None of the newborns were HIV-infected at 6 months of age (n = 59, one death at day 3). Only one severe adverse event occurred due to saquinavir (maternal grade 3 hepatotoxicity). CONCLUSION: SQV/r 1000/100mg twice daily seems to be effective and safe in HIV-infected pregnant women with adequate saquinavir C(min).