To describe and compare the changes in renal function between HIV-1 infected adult patients receiving antiretroviral therapy (ART) with and without tenofovir (TDF). The population consisted of 40 patients starting a TDF-containing regimen and 388 patients starting regimen not containing TDF, and followed during 42 months. The estimated glomerular filtration rate (eGFR) was calculated using the Cockroft-Gault and MDRD equations and modeled separately for the first 12 months and the subsequent period. Between baseline and 12 months, the eGFR decreased significantly in patients receiving TDF (-10.40 ml/min), whereas it increased in the other +4.33 ml/min). A significant variability in the eGFR trajectories of patients receiving TDF was observed; 12 (30%) of them experienced a persistent decrease, 5 (12%) had an initial transient increase, and 23 (58%) a steady slow increase in eGFR. The characteristics at baseline of the patients with persistent decrease were not different from the other patients but their immune reconstitution was impaired. After 12 months, patients receiving TDF experienced a higher rate of transition from mild renal impairment (60-90 ml/min/1.73 m(2)) to moderate renal impairment (30-60 ml/min/1.73 m(2)) when compared with patients not receiving TDF. A significant though moderate decline in the renal function was observed in one-third of the patients receiving TDF compared to patients not receiving TDF. Moreover, this impairment was persistent after the first year of treatment.