Plasma creatinine dosage is the easiest way to evaluate renal function but glomerular filtration rate estimation from cockcroft or MDRD formulae is a much better indicator of renal function. Other markers like cystatin C may be used. None of these markers has been validated in HIV patients. Therefore our study is aimed at comparing validity of creatinine clearance estimation with Cockcroft and Gault and MDRD formula and cystatin C compared to the gold standard measurement of glomerular renal function.