Pathological changes occurring in the tissues of rabbits, orally infected with 50 000 embryonated eggs of Toxocara canis, were studied. Inflammatory foci were observed in different organs. The migrating larvae produced gross lesions, like numerous greyish milk spots on the surface of the lungs and liver, and slight enlargement and pale appearance of the kidneys and spleen. The histopathological lesions observed in the liver were haemorrhages, nodule formation, leukocytic infiltration, necrosis and giant cell formation. The lungs showed congestion, oedema, emphysema and infiltration of neutrophils, eosinophils, macrophages and giant cells. The changes observed in the heart and spleen were congestion and haemorrhages. The small intestine had multiple nodules infiltrated by lymphoid cells. The histopathological changes in the brain included congestion, perivascular cuffing and infiltration of mononuclear cells.