The aim of this paper is to establish the haematological and organic changes in halothane-sensitive and halothane-resistant pigs in the course of experimental anisakiosis. Experiments were carried out on two groups of pigs (3 animals each). The pigs from the first group were given fifty A. simplex B larvae, the pigs from the second one received ten larvae and then again fifteen larvae each after the 5th and 6th days. The number of leucocytes, neutrophiles, lymphocytes, monocytes and eosinophiles was greater - different in both series, but similar in halothane (stress) - resistant and - sensitive pigs. In the case of sensitive pigs much greater reactive changes were found in the stomach submucosa than in that of resistant pigs. In this group of pigs nematode larvae have also been traced in the submucosa of the same organ.