Hot seasons of the year are accompanied by significant losses for dairy farmers. Stress in cattle breeding causes various physiological disorders of vital organs and systems, including nervous, cardiovascular, and endocrine pathologies. Heat Stress (HS) affects the reproductive performance of cows at various physiological stages (pregnancy, calving, the postpartum period) and that manifests in fertility decrease and even leads to culling. Understanding the mechanisms and effects of high temperatures on the reproductive function of productive animals will allow minimizing the impact of HS by implementing appropriate heat-reduction strategies, adjusting nutrition, and breeding heat-tolerant cattle. Thus, a well-considered and timely implemented HS control strategy will prevent reproductive losses and reduce economic losses in the dairy industry.