The author reports an autopsy case of a two year old child with massive intestinal ascariasis and malnutrition, presenting the migration of two adult Ascaris lumbricoides through the left kidney into the pyelo-ureteral system. As a result she developed acute pyelonephritis and ureteral obstruction. Previously the worms left the intestine into the peritoneal cavity (lesser sac) through a duodenal cleft. Factors contributing to the migration of the roundworms by those pathways are discussed.