The effect of Propranolol and Levonor Polfa on a sexual activity and quality of semen of bulls (young about 500 kg, grown-up about 900 kg) have been observed. Fifty four animals upon four young (1, 2, 3, 4) and three grown-up (5, 6, 7) under groups has been distributed, then intramsucularily injected: young and grown-up bulls a physiological salt saline (1), Levonor (2, 5), Propranolol (3, 6) and Propranolol and Levonor (4, 7). The drugs caused an increase of sexual activity in every group. Certain minor changes in intensity of ejaculation have been noted in young animals after the following applications: an increase of ejaculate volume after the injection of physiological saline, a decrease after Levonor. A statistically significant increase of the amount of ejaculated semen has been noted after the application of Propranolol and Levonor. In groups under observation composed of grown-up animals a statistically significant decrease of the amount of ejaculated semen after the application of Levonor and a minor increase after the application of Propranolol and both Propranolol and Levonor have been noted. The concentration of spermatozoons did not change after the injection of physiological saline. Levonor decreased but Propranolol slightly increased the concentration of spermatozoons. A statistically significant increase of spermatozoons concentration in ejaculates of young and grown-up bulls has been noted after the application of both Propranolol and Levonor. A similar effect was achieved in Propranolol injected bulls. Injections of Levonor decreased a percentage of acidophylic leukocytes in blood after 4 hours since treatment.