The aim of this work was to find the influence of horizontal and vertical teat position of ewes on traumatisation of mammary gland in the process of milking. The measurements took place in two breeds of sheep (40 East Friesian sheep – EF, 40 crossbreed Sumavska sheep and Lacaune – SxLC). The surface temperature of the udder with teats positioned horizontally and vertically was monitored by thermographic method before and after milking in the middle of the lactation period. Temperature records were evaluated by TermaCAM Reporter 2000 and the data were statistically analysed by the Statistica software. Significant difference in the surface temperature measured after milking was proved between udders with vertically situated teats in comparison to udders with horizontally situated teats only in the EF sheep. Statistically significant traumatisation of the mammary gland was found in East Friesian ewes with vertically situated teats of mammary glands.