Toxocariasis is a parasitic zoonosis caused by infestation of humans with larvae of Toxocara canis, the common roundworm in dogs. Two syndromes have been identified : visceral larva migrans and ocular toxocariasis. In this study we were characterized proteinase activity in crude extracts from liver, lung, kidney and heart of mice infected with Toxocara canis and the dynamics of their changes in different stages of disease. The optimal pH was 5.5. In liver of mice infected with Toxocara canis, the maximun activity of proteinase was observed in 5 day post infection. In lung, the activity reached its maximun on 5th day in A group (infected with 100 embryonated eggs), and on 5th week in B group (infected with 50 embryonated eggs). In kidney, the maximum activity was shown at 6th week in A group, and in B group was shown at 10th day. In early infection, the activity reached its maximun in heart of mice infected with Toxocara canis. As we could see, the dynamics of the changes of proteinase activity in mice is similar in the case of the disease with other biochemical and immunological indices observed in toxocariasis.