A 63-year-old man underwent a living-related kidney transplantation secondary to Wegener granulomatosis. The early postoperative course was uneventful, and the patient was discharged with good renal function. On postoperative week 3, the patient presented with complaints of leg swelling and abundant watery discharge from the lower end of the surgical wound. Technetium-99m mercaptoacetylglycine-3 (Tc-99m MAG3) renal scan showed indeterminate tracer accumulation overlying the pelvic region. With a Foley catheter in place, the accumulation in the pelvis was slightly more than expected bladder activity. Suspicion for a possible urinary leak was raised. For that reason single photon emission computed tomography/computed tomography fusion (SPECT/CT) imaging was performed, which showed tracer accumulation associated with fluid collection in the pelvis anterior to the transplanted ureter, thus proving the presence of a urinary leak. This case report shows the usefulness of SPECT-CT imaging for proving questionable urinary leak of renal transplants.