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In the beginning of 1990s, the programme of formation of synthetic population of Slovak Dairy sheep (SD) was launched. Some flocks were involved into performance testing; the establishment of the breed was divided into two periods: first, crosses of local breeds (Improved Valachian, Tsigai and Merino) with improving breeds (Lacaune, East Friesian) of various proportions were formed; second, a close (inter se) breeding scheme within the crossbred population was applied. Parents of the next generation were chosen on the basis of breeding values for milk yield and litter size. At present, five thousands female SD individuals are included in the performance testing; 35 % yearling females enter the breeding scheme each year; a total, 50 thousands SD ewes are kept in commercial flocks. Milk and reproduction traits of SD were analyzed using mixed model methodology that included fixed and random effects. In similar way growth traits were analyzed. Milk traits analyses included 20,511 milk records belonging to 11,026 ewes kept in 52 flocks during the period between 1995 and 2015; reproduction traits analyses included 30,034 litter size records belonging to 9,671 ewes kept in 26 flocks during the period between 1997 and 2015. The standardized milk yield (SMY) and average daily milk yield (ADMY) increased more than twice: 79.8 ± 5.36 l (1995) vs. 164.0 ± 2.04 l (2015) and 495.1 ± 33.5 ml (1995) vs. 1035.3 ± 12.8 ml (2015), respectively. In ten percent of the most productive ewes, SMY was equal to 257.6 l, ADMY was equal to 1604 ml and dry matter was equal to 26.6 kg. Fat and protein contents decreased from 7.82 ± 0.101 % (1995) to 7.27 ± 0.040 % (2015) and from 5.83 ± 0.043 % (1995) to 5.69 ± 0.017 % (2015). Ewes of SD have good udder traits. Litter size in top 50 % flocks was above 150 %. Average daily gains from birth to weaning were 0.26 kg (female lambs) and 0.30 kg (male lambs). The population of SD was recognized as a breed in 2017.