We investigated the effect of food on the steady-state pharmacokinetics of a proprietary fixed-dose combination (FDC) tablet containing tenofovir disoproxil fumarate (TDF)/emtricitabine/efavirenz. Fifteen Ugandan HIV-1 patients at steady-state dosing with TDF/emtricitabine/efavirenz were admitted for 24-hour intensive pharmacokinetic sampling after dosing in the fasting state. Blood sampling was repeated seven days later with TDF/emtricitabine/efavirenz administered with food (19 g fat). Drug concentrations in plasma were determined by liquid chromatography and tandem mass spectrometry. Geometric mean ratios (GMRs) and confidence intervals (CIs) of parameters were calculated (reference, fasting). For efavirenz, GMRs (90% CIs) for C(max), AUC(0-24), and C(24) were 1.47 (1.24-1.75), 1.13 (1.03-1.23), and 1.01 (0.91-1.11), respectively. Corresponding GMRs were 1.04 (0.84-1.27), 1.19 (1.10-1.29), and 0.99 (0.82-1.19) for tenofovir, 0.83 (0.76-0.92), 0.87 (0.78-0.97), and 0.91 (0.73-1.14) for emtricitabine. Stable patients may take the FDC without meal restrictions. The FDC should be taken without food by patients experiencing central nervous system toxicities. ; This work was funded by the Health Research Board, Ireland, through a Global Health Research Award (GHRA07/09). It was also funded by the Gilead Foundation, and the European and Developing Countries Clinical Trials Partnership