Ecological and climatic factors have an impact on the health, productivity and reproduction of the cattle. The goal of this work is the study of physiological status of servicing bulls reared under ecological and climate conditions of the Altai region, by defining the differences between Red-Steppe, Simmental and Black-and-White breeds in spermatogenic, hormonal, biochemical and hematological parameters. Samples of peripheral blood and ejaculates were taken from 48 grown-up servicing bulls (average age 5.6±0.3 years) in autumn period. It was established that Red-Steppe bulls have higher concentrations of nonorganic phosphorus, leucocytes, erythrocytes, hemoglobin, hematocrit and erythrocyte sedimentation rate in comparison with animals of Simmental breed, and the hemoglobin concentration and hematocrit are also higher in comparison with Blackand-White breed. It was noted that bulls of Black-and-White breed have a higher level of cortisol in comparison with the other breeds. The lowest level of serum urea and total protein and increased serum activity of creatine kinase and γ-glutamyl transferase, as well as the heaviest body weight were observed in Simmental breed bulls. The differences between breeds in a wide spectrum of physiological measures reflect not only genetically determined peculiarities of homeostatic mechanism, but also may reflect different ability to adapt to local ecological and climate conditions of the Altai region. Spermatogenic, biochemical and hematological measures in bull sires reared in the Altai region were similar to those in bulls bred in other Russian regions and some other countries. The measures reported could serve as reference values and therefore represent 'normal' values of physiological status for these bull sires reared in this ecological and climatic zone, but could be utilized in further studies for comprehensive monitoring of cattle breeding stock in other ecological and climatic zones of the Siberian region of Russia.