We prospectively analyzed the impact of post-transplant infections on the renal function in 532 stable renal transplant recipients (M=340; F=192) over a period of 5 years. Their age ranged from 3-75 years (40+14 years). During the follow-up period, 52 patients expired and 64 lost on followup. We defined renal impairment (RI) as a persistent rise in serum creatinine above 20% from baseline value. 495 episodes of RI occurred in 269 recipients. This included 180-36% episodes of acute rejection, 53-10.7% Cyclosporine toxicity, 236-47.7% infection related renal impairment [IRRI] and 26-5.3% others. The severity of renal failure is less in IRRI (100+90.2) than that of acute rejection (166+127.1), but was more than that in cyclosporine toxicity (50+42.2). Sites of infection in IRRI were urinary (33%), respiratory (26.3%), septicemia (15.7%) and others (25.4%). Episode of IRRI occurred more frequently in LURD (159-67.4%) compared to LRD-RTR (50-21.2%). Occurrence of IRRI is more significantly higher in patients on triple drug immunosuppression (IS) (34.3%) than those on two drug IS (13.2%) (P=or<0.01). Ecoli (23.1%), Pseudomonas (11.1%), Salmonella (8.8%), Klebsiella (8.8%) and Staphylococai (8.3%) were the major organisms producing IRRI. IRRI is frequent (27.8%) during the first six months. Present study denotes that IRRI is a major cause of acute failure in RTR.