Mammary gland neoplasms in cats are at the top of the list of the most common nosological diseases among domestic animals; more than half of the tumors appear as malignant. Veterinary practitioners have many questions about the prevalence of breast tumors in cats, depending on age, breed and seasons of the year. The article presents the results of diseases prevalence of benign and malignant breast tumors in cats kept in the conditions of Bishkek. The characteristic of macroscopic and microscopic studies of benign and malignant breast tumors in cats at different periods of life and depending on the breed is also described. Studies were conducted in the period from March 2018 to March 2019. Morphological methods were used in the study of breast tumors. As a result of our research, we established the morphological forms of benign and malignant breast tumors in cats. Among benign neoplastic breast diseases in cats, breast lipoma was observed. Also among the malignant tumors of the breast met highly differentiated, moderately differentiated and poorly differentiated breast adenocarcinomas malnutrition and necrosis as well as the rare phylloid (leaf-shaped) fibroadenoma of the mammary gland which makes up only 0.3-0.5 % of all breast tumors.