We studied the clinical and pathological features of 26 patients with renal carcinoma of a solitary kidney, including 6 treated at this hospital. Four patients had a contracted kidney and 22 had previously undergone nephrectomy. Partial nephrectomy was performed in 16 patients, enucleation of the tumour in 5 and radical nephrectomy in 5 because of the size of the tumour. Ex vivo surgery was carried out in 4 patients. The duration of ischaemia ranged from 15 to 365 min but was longer in those who underwent ex vivo surgery (149 to 365 min). Of the 21 patients who underwent partial nephrectomy or enucleation, the serum creatinine level increased (greater than or equal to 2.0 mg/dl) post-operatively in 16 patients, of whom 9 required temporary haemodialysis. No recurrence has been noted in those who underwent partial nephrectomy, but 1 patient who underwent enucleation of the tumour developed a solitary pancreatic metastasis 2 years 6 months after surgery and was treated by a partial pancreatectomy. Kidney-preserving surgical procedures are considered to improve the quality of life, but careful follow-up is necessary.