A cross sectional study was carried out to estimate prevalence of clinical mastitis on udder quarters level and to determinate the quarter risk factors associated with the development of clinical mastitis during lactation.The individual risk factors included assessments of parity, season of year when case of clinical mastitis was occurred, conformation characteristics of udder quarters and teats and distance from front and rear teat end to the floor. Cows with clinical mastitis were detected by clinical examination of the udder quarters and determination of abnormalities in milk.The quarter level prevalence of clinical mastitis was 15.06% per lactation, out of which 3.32% were front left, 3.10% front right, 4.28% rear left and 4.28% were rear right quarters. The prevalence of udder quarters affected with clinical mastitis tended to increased with increasing the parity, from cows in first to the third parity, and then begins to decline slightly. The rear quarters frequently manifested form of clinical mastitis (49.39%) in relation to the front one (33.04%), and in 17.55% of the cases there were affected either, front and rear quarters. In the most cases of clinical mastitis there was affected only one quarter of the mammary gland (74.35%), two quarters in 20.13%, three quarters to 3.61% and four quarters were affected in 1.89% of the cases of clinical mastitis.The method of General Linear Model, unvaried procedure, revealed that prevalence of clinical mastitis on quarter level significantly (p<0.01) differed with the season of year when case of clinical mastitis was occurred and scoring categories for position of rear udder quarters.