The ELISA test was used to detect antibodies against Mycoplasma agalactiae in the blood plasma and milk of ewes belonging to Experimental Stations I and II of the Agricultural University in Lublin. The age of ewes was between 2-7 years and they were from the first to sixth lactation period of about 100 days duration. The ewes were free of infectious diseases and the blood and milk samples were taken in the 15th, 45th, and 75th days of lactation. For detection of antibodies against Mycoplasma agalactiae the kit of Dr. Bommeli AG (Switzerland) and evaluation unit for ELISA of Magpol (Poland) were used. Of 76 ewes of group I, only in 4 appeared a higher level of antibodies against M. agalactiae, in comparison to negative control values, but this was significantly lower than the level of positive controls. In the samples of milk of group I the level of antibodies was in the range of negative controls, and only slightly increased in two cases, but not to the range indicating M. agalactiae infection. In the samples from 4 ewes belonging to group II, although the level of antibodies was higher than the negative control values it was still in a range much lower than positive control values. In the milk samples of 54 ewes from group II the level of antibodies was in the range of negative controls and slightly augmented in 17, but below the threshold indicating infection with M. agalactiae. The obtained results do not prove the presence of deseased state of udder caused by M. agalactiae in either group of ewes.