Few data exist on the safety of tenofovir (TDF) in HIV-infected patients with preexisting renal dysfunction. We report 12-month changes in renal profiles among 19 such patients (6 patients with history of and 13 patients with current renal disease) in the HIV Outpatient Study (HOPS) who initiated TDF-containing highly active antiretroviral therapy (HAART) during 2001-2005 with TDF dosed mostly at 300 mg once daily. At baseline, the median estimated glomerular filtration rate (GFR) was 49 mL/min/1.73 m(2) and the median CD4(+) cell count was 322 cells/mm(3). Patients had a median 12-month change in estimated creatinine clearance from baseline of -0.3 mL/min (range, -32.2 to +23.6) and the median change in GFR of -0.1 mL/min/1.73 m(2) (range, -49.8 to +29.5). We observed confirmed worsening of kidney disease stage in 5 of the 19 patients during follow-up. TDF use can be considered in patients with preexisting or current renal dysfunction who have limited antiretroviral treatment options, require TDF for fully active antiretroviral regimen, and can be closely monitored for incident worsening of renal function.