Two brothers with the neonatal presentation of dominant polycystic kidney disease are reported. The first infant died shortly after birth; autopsy revealed polycystic kidneys. The second infant had two markedly enlarged kidneys at birth. Intravenous pyelography at the age of 10 days showed typical images as observed in the recessive form of polycystic kidney disease. Kidney biopsy showed cystic dilation involving all parts of the nephron; the liver biopsy did not show any abnormality. Severe arterial hypertension was a major problem in the first six months of life. At the age of 3 and 5 years, respectively, the patient developed intracerebral hemorrhage, which was due to a complex intracerebral arteriovenous malformation. At the age of 8 years the boy had chronic renal failure and spastic quadriplegia. Previously unsuspected polycystic kidneys were found in the father during the family study.