Tubulointerstitial nephritis occurs as a result of primary injury to renal tubules and interstitium. The acute form is often due to allergic drug reactions or to infections. Renal scintigraphy is a useful noninvasive diagnostic procedure for the evaluation of renal transplant complications. The aim of this study was to evaluate Tc-9m DTPA and Tc-99m MAG3 renal scintigraphy findings in renal transplant recipients with acute tubulointerstitial nephritis. A total of 60 renal transplant recipients were evaluated using both tracers. Out of these 60 patients, 5 had biopsy proven acute tubulointerstitial nephritis. Ten recipients with normal graft function were included as control group. Tc-99m DTPA and Tc-99m MAG3 renal scintigraphy was performed one day apart. For both studies, images were acquired every second for 1 minute (perfusion) and every 30 seconds for 20 minutes. The images were interpreted in relation to perfusion pattern, extraction ability and parenchymal retention of activity. Results: Perfusion was impaired in all patients in both studies. Concentration was decreased in all patients on DTPA and renogram curves in 2 patients exhibited a slightly descending pattern without a concentration peak. Initial uptake of tracer was decreased in all patients on MAG3. Significant parenchymal retention of activity was observed in all patients for both tracers. In conclusion, all patients with acute tubulointerstitial nephritis had abnormal perfusion and function with both agents. Although these findings can be observed in other allograft pathologies, a slightly descending renogram curve without a concentration peak on DTPA and significant parenchymal retention combined with impaired perfusion and decreased initial uptake on MAG3 might suggest the presence of acute tubulointerstitial nephritis.