On a small closed population of Mis sheep the relationship was studied of the influence of inbreeding on body weight growth from birth to the age of 18 months and sperm DNA fragmentation in rams. Two groups of male lambs were used. First was composed of outbred, while the second of inbred animals with inbreeding coefficient over 25%. Differences in body weight and daily gain related to the presence of inbreeding in the pedigree were not found significant (P>0.05). The mean value of sperm chromatin damage in rams of the outbred group varied from 1.93 to 12.37%, (mean = 7.32%) and in inbred group from 13.76 to 37.67% (mean = 25.23%). Significant difference was identified between the outbred and inbred rams in the mean percentage of sperm damaged (P<0.01).