Based on the results of the study, methods for determining the fertility of replacement pigs in the conditions of an industrial pig farm have been improved. The effectiveness of the proposed "Complex method for determining the fertility of replacement pigs in industrial conditions" is shown. An assessment was made of the hormonal status of replacement pigs in the ontogenesis phases critical for the development of the reproductive system - before the first estrus (before puberty) and immediately before insemination (maturity of the body); features of the manifestation of the immobility reflex in these gilts under conditions of artificial insemination. When applying the developed methodology for determining the timing of insemination of pigs, its efficiency increases - the percentage of pro-hollowness decreases from 5.68% to 1.29%, which leads to a reasonable expenditure of labor costs for the preparation of sperm doses and insemination, more rational use seed production at the same financial costs for the technique itself.The level of sex hormones (estradiol, testosterone, cortisol and FSH) in the blood serum of physiologically healthy replacement pigs of the Duroc breed in the phases of ontogenesis that are critical for the formation of the reproductive system - in the period before the first estrus and in the period after body maturation (immediately before insemination) allows you to quickly determine fertility in replacement pigs. The use of the developed "Complex method for determining the fertility of replacement pigs in industrial conditions" contributes to the effective use of the breeding stock