Renal functional reserve (RFR) is the kidney capability of increasing its basal glomerular filtration rate (GFR) at least 20% after an adequate stimulus. Renal disorders have been reported in seropositive HIV patients, particularly the decrease in glomerular filtration rate (eGFR), nephrotic syndrome, and proximal tubular deficiency associated with the disease itself or the use of some anti-retroviral treatments. Thus, it was decided to carry out a prospective study in order to evaluate if RFR test was preserved in naive HIV patients.