Karakul ewe lambs born to ewes which lambed in summer, winter and spring were randomly allocated to pen and veld nutrition. Age at sexual maturity and body mass every 14 days, as well as lambs born up to respectively 45, 41 and 50 months of age were recorded. All lambs were slaughtered for their pelts within 24 h after birth. The average (± SD) age at sexual maturity of ewe lambs (pen and veld nutrition) born during summer, winter and spring showed a season of birth effect (424,6 ± 154,3; 351,8 ± 117,8 and 341,4 ± 153,6 days respectively). A highly significant (P<0,01) interaction was found between season of birth and nutrition with ewe age and body mass at first conception. The average (± SD) body mass at sexual maturity of ewes receiving pen and veld nutrition during the experimental period was 45,2 ± 8,0 and 34,2 ± 5,9 kg (P<0,01) respectively. Pen nutrition positively influenced (P<0,01) reproductive ability of ewes born during the summer, winter and spring. The reproduction rate, measured from birth during the experimental period of ewes receiving pen and veld nutrition was 1,18 and 1,00 lambs/ewe/year respectively. Ewes attaining sexual maturity in the first and second breeding season after birth, lambed 4,2 and 3,2 times respectively during the experimental period