A trial was carried out on thirty pregnant Ossimi ewes aged 3-4 years, belonging to the Animal Production Research Station at Sids, with live weight ranging between 45 to 50 kg. The animals were divided at randomly into 3 groups of 10 ewes each with almost equal mean live body weight. Animals were given maintenance and production diets according to their average body weight (NRC 1988). Concentrate feed mixture composed of 22% decorated cotton seed cake, 20% molasses, 44% wheat bran, 10% yellow maize, 2.5% ground limestone and 1.5% common salt. Water was provided ad-libitum during the whole experimental period with clover hay and rice straw. The trial started 1^st January and ended 1^st June 2018 (5 mo. /wool growth) and included 3 groups; Control group; received the basal diet only without any supplements, the first group; was given the basal diet plus 0.23 gm selenoprotein / kg dry matter/ head/day (0.5mg available selenium), the second group; was given the basal diet plus 0.33 gm selenoprotein / kg DM /head /day (0.7mg available selenium). The trial included two periods, the first three months of pregnancy and the last two months of pregnancy. The aim of this study was to study the effect of adding selenium to the diet of pregnant Ossimi ewes on wool growth. Physical and mechanical wool properties were assessed besides estimation of Glutathione peroxidase (GPX) enzyme activity. Results showed that during the first 3 months of pregnancy, there was significant difference (P≤0.05) among groups in FD, SST, ELO % and GPX enzyme activity, while there was no significant difference in STL. But in the last two months of pregnancy there was significant difference (P≤0.05) among groups in STL, FD, SST, ELO % and GPX enzyme activity.