The diagnostic tools used to achieve an assessment of allograft dysfunction should be as noninvasive as possible, because kidney graft recipients are fragile patients and quite often the need is for repeated investigations. In order to evaluate the reliability and accuracy of such a method, in this case scintigraphy with 99mTc-DTPA, the authors retrospectively studied 2 groups of kidney transplanted patients, having two different basic immunosuppressive regimens: group A--86 patients--taking steroids and azathioprine; group B--93 patients--taking steroids and cyclosporine. A total of 722 scans were retrospectively compared with scintigraphic information: 196 episodes of allograft dysfunction were due to acute rejection: 118 in group A, 78 in group B; 117 episodes were due to ATN: 75 in group A, 42 in group B; 11 episodes were ascribed to CyA acute nephrotoxicity. Group A and B behave differently in respect of the perfusion index. Only in group A were perfusion indexes statistically different in rejection, ATN and nephrotoxicity. Anyway, it must be stressed that, even if in group B, scintigraphy cannot be considered an accurate diagnostic method, it is somehow a helpful tool because it gives information about a worse perfusion of the graft, independently of the underlying pathology.