To the Editor.— In the report entitled, Allotransplantation for Bilateral Renal Tumors, (210:1721, 1969), Case 2, known to have tuberous sclerosis, had what appears to have been benign mesenchymomas (hamartomatous angiomyolipoma) in both kidneys necessitating the removal of one. In a similar case (Arch Intern Med120:70-80, 1967), a patient having benign mesenchymomas bilaterally without evidence of tuberous sclerosis underwent a right nephrectomy in 1962 and a left nephrectomy in 1965, necessitating the implantation of an arteriovenous shunt and maintenance extracorporeal hemodialysis. A renal homotransplantation from a fraternal twin (by Dr. David Hume) in 1966 was successful. This should lend further strength to Dr. Jochimsen's projection of eventual successful transplantation in his patient when the patient's condition eventually warranted removal of the remaining kidney.