The article describes the reactive changes of rats’ reproductive system after spirulina biomass exposure. The study involved 80 female and 32 male rats of one month of birth, weighing 190-210g divided equally into eight groups. The animalas received suspension of spirulina biomass in accordance with the group affiliation. Suspension of spirulina biomass was prepared on distilled water and was daily administered to the animals intragastrically in accordance with the group affiliation and time schedule at a dose of 10 mg / 100 g body weight, 1 ml of volume. The control group received 1 ml of distilled water. The animals were daily monitored. The following parameters of the rats were analyzed depending on the duration of spirulina intake: amount of the atretic bodies and Graafian follicles, the follicles with a single granulosa cells layer, the follicle with two or more granulosa cells layers, the testes mass ratio; the adnexa mass ratio; the prostate gland mass ratio; % of sperm cells pathological forms. It was established that spirulina biomass improves the physiological activity of the reproductive system in male and female rats.