Sotos syndrome is characterised by accelerated growth, acromegalic appearance, mental retardation and social maladjustment. Most cases are sporadic, but familial cases have also been reported. We report a case of Sotos syndrome presenting with chronic renal failure due to autosomal dominant polycystic kidney disease (ADPKD). Ultrasonographic examination of the patient, his father and other family members revealed polycystic kidneys. Renal failure was present only in the Sotos case, who also had considerably larger cysts than other family members. We suggest that the underlying mechanism responsible from the somatic overgrowth in Sotos syndrome may also be linked with the development of larger cysts and earlier onset of renal failure in ADPKD. Although Sotos syndrome has been associated with urological abnormalities, chronic renal failure is very rare. To our knowledge, Sotos syndrome associated with ADPKD has not been reported before.