In years 1989—1990 necropsy was performed on 38 lamb carcasses. The presence of Ascaris suum was found in intestines of 5 lambs. The parasites were not mature sexually since no eggs were observed in the wombs of the females. The lambs originated from a farm specializing in sheep breeding. The age of the animals ranged between 3 and 4 months. Infestation took place on a common sheep-run where lambs and piglets were kept together. In young pigs the invasion of Ascaris suum was noted by coproscopic examinations.