The reflex sympathetic dystrophy syndrome (RSDS) in organ transplant recipients has only previously been reported in patients treated with calcineurin inhibitors. We retrospectively analyzed 393 renal transplant patients treated with sirolimus, 9 of whom developed RSDS. All the patients reported varying degrees of pain in the legs, affecting the knees, ankles, and/or feet, plus cutaneous erythema. The onset of pain ranged from 1-6 months after transplantation. At the time of diagnosis of RSDS, the mean serum creatinine was 1.4 mg/dL (range 1.0-1.7) and bone scintigraphy with 99mTc pyrophosphate showed increased uptake in all cases. The symptoms remitted 3-10 months after treatment (mean, 4 months) with calcitriol, with or without nifedipine or calcitonin, and in one case with suppression of sirolimus. We conclude that sirolimus therapy may induce RSDS in renal transplant recipients.