The present study was carried out on 43 herds belonging to farmers from the District of LublinThe present study was carried out on 43 herds belonging to farmers from the District of Lublinin the period 1999–2004. The data collected from 22736 trial milkings was used to analyse 24-hour milk efficiency, milk fat and protein content as well as SCN and the percentage share of milksamples in individual milk quality classes in relation to the number of animals in the herd in whichthey were utilised ( 15, 15–30 and >30 animals), milk efficiency levels of the herd (<4000, 4001–5000 and >5000 kg of milk FCM), cow breeding system (tethered, free stands) and milking methods(milk churns, duct, milking parlour), consecutive lactation periods (I, II, III, IV and furtherperiods as a total) and their phases (1–3, 4–7, 8–10 and 11 and further months), season of the year(XII, I, II – winter, III, IV, V – spring, VI, VII, VIII – summer, IX, X, XI – autumn). The datacollected was then analysed using the least square method, and the percentage share of milk samplesin individual milk quality classes was analysed by means of a chi2 test. It was shown that theinfluence of the number of animals in the herd and milk efficiency level of the herd, cow breedingsystem and milking methods used exerted influence on the 24-hour milk efficiency as well as milkfat and protein content. The highest milk efficiency and milk fat and protein content was observed inanimals bred in free-stand cowsheds and utilised in herds with the number of animals above 30 and milkefficiency levels higher than 5000 kg of milk FCM, milked in milking parlours. The factors which differentiatedSCC in milk as well as milk samples share in various milk quality classes most were consecutive lactation period and its phase, herd size and its milk efficiency level as well as the milking method used and season of the year. In consecutive lactations, the number of somatic cells in milk increased and its percentage share in the extra class decreased. The lowest number of somatic cells in the milk and its highest share in the extra quality class was noted in winter and spring in herds with milk efficiency of up to 4000 and above 5000 kg FCM and in the case of cows tethered in cowsheds milked with duct systems.