The nonspecific resistance of cows at the interlactation period was studied for the forecasting of the postnatal period progress in the conditions of the Republic of Belarus. Influence of the complex preparations Erimetrinis and Richometrinum on restoration of cow reproductive function was investigated. It was established, that the developed new complex preparation Erimetrinis possessed the uterotonic, antiphlogistic, pathogenetic and stimulating action. Evaluation of the presented preparation was tested have under production conditions and confirmed its high efficiency. After application of Erimetrinis there was noted a fast restoration of both endometrias histostructure, indices of cellular protection, and cow clinical characteristic. Microflora which was discharge from cow uterus content, which were sick with postnatal purulo-catarrhal endometritis, was sensitive and high-sensitivity Erimetrinis and had a zone of growth inhibition from 19,6 up to 36,1 mm, while after Richometrinum application it was sensitive except for staphylococcus and diplococcus in which the growth inhibition zone was from 15,1 up to 15,4 mm. Study of indicators of bactericidal activity of cow blood serum in course of treatment with the Erimetrinis it was established, that starting from the fourth day of the treatment the analysed indicator increased up to 56%, and by the moment of the clinical recovery it was 82,4+/-2,16%. Indicators of lysozymic activity of blood serum at the moment of cow recovery were 13,4+/-1,35 mmol/l. Essential changes were marked in the phagocytic activity of leukocytes, phagocytic numbers and phagocytic index. Cows which were subjected to treatment with Richometrinum all mentioned above indicators were increasing starting from the tenth day of treatment beginning, and clinical recovery was stated on 7,4 days later than after Erimetrinis application