A total of 3592 cows, which first calved in 2003 and completed their 305-day lactation, were kept in a tied (2580 animals) or loose housing system (1012 animals). All animals were assessed for udder conformation between 15 and 180 days after calving. Control milkings were performed once a month for 10 consecutive months to determine somatic cell count (SCC) in milk. The SCC in milk was found to vary according to the housing system and was much lower in loose-housed cows. There were highly significant relationships between the conformation of different parts of the udder and SCC in milk samples. Milk of cows with fore udder attachment, given a score of over 5 points in both housing systems, was characterized by the lowest SCC. For rear udder attachment, similar or lower SCC were observed for scores of 4-6 points than for scores of 2-3 points, when SCC was the highest. Animals scoring over 5 points for median suspensory ligament and udder placement were characterized by the lowest SCC in milk. SCC in milk decreased as udder attachment became stronger and higher, regardless of the animal housing system. Cows with closely spaced rear teats and centrally located front teats showed low variation in milk SCC. In the loose system, teat length did not significantly affect SCC in the analysed milk samples, but a tendency towards this occurred in the tied housing system.