A case of massive bilateral angiomyolipomas (AML) associated with tuberous sclerosis in a 33-year-old woman is reported. She was hospitalized because she had been experiencing abdominal fullness and epigastralgia. Several imaging studies revealed massive bilateral renal tumors and she was diagnosed as having renal AML associated with tuberous sclerosis. Left nephrectomy was carried out after renal arterial embolization for intratumor hemorrhage. Two years after left nephrectomy, nephron-sparing surgery (tumorectomy) for right AML was done because of an increase in the size of the right renal AML and she hoped for a future pregnancy. The left kidney with AML weighed 5700 g and the right AML weighed 1700 g. Postoperative serous creatinine did not differ from that before operation and an increase in the size of the residual tumor was not observed 8 months after operation. We consider that tumorectomy is an effective therapy in patients with a very large tumor involving a solitary kidney.