Patient size has been suggested as a risk factor in kidney transplantation. We have followed a recipient of a cadaver kidney who became massively obese (232 kg, 511 lbs) 5 years posttransplantation. He has maintained stable renal function with no rejection episodes and at 5 years has a measured serum creatinine of 2.2 mg/dL, creatinine clearance 42 mL/min, and urinary protein excretion of 320 mg/24h. Both oral and intravenous cyclosporine (Sandimmune) pharmacokinetic studies were done on a steady-state dose of 150 mg, which represents 0.65 mg/kg per dose. The patient exhibited very high bioavailability, F = 95%, and an oral elimination T1/2 of over 21 hours. These data confirm that stable cyclosporine delivery in very obese recipients can be sustained by dosing normalized to the ideal body weight and trough level monitoring.