Defined was the acute toxicity LD50 of a 7.5 per cent solution of the Levamizol-Pharmachim preparation following its subcutaneous application to albino mice and rats. Sheep and pigs were also injected subcutaneously with the same solution and their tolerance of the preparation was defined at rates of 7.5, 22.5, and 37.5 mg per kg body mass. Comparative clinical testing was carried out of the 7.5 per cent solution of Levamizol-Pharmachim and Nilverm (ICI, England) with regard to their action against sexually mature strongylates in sheep and against swine ascaridiasis and Esophagostomum infection. It was found that the subcutaneous injection of albino mice with a 7.5 per cent solution of the preparation at the rate of 90 mg/kg was in fact the LD50 dose with this route of application. In the case of albino rats LD50 turned out to be 120 mg/kg. Levamizol had good tolerance with adult swine and pigs at subcutaneous introduction in a dose of 7.5 mg/kg. Death cases were recorded with these animals with the use of 37.5 mg/kg, which was 5 times the ED50 dose. The preparation was shown to be suitable for both therapeutic and prophylactic worming of sheep and swine.