Tenofovir (TFV) is a nucleotide analogue active against HIV and hepatitis B virus. Although TFV rarely affects the glomerular function, abnormalities in the kidney tubular function appear to be quite common. The relationship between TFV exposure and kidney tubular dysfunction (KTD) was examined prospectively in 92 HIV-infected individuals. Median TFV plasma trough concentration was higher in patients with KTD than in the rest (182 vs. 106 ng/ml; P = 0.001). This dose-dependent effect further supports an involvement of TFV in KTD.