Ewes with single lambs received either sufficient feed to maintain body condition during lactation (high plane) or the quantity of feed was reduced so as to result in an average loss of approximately 20% in body mass (low plane). The suckling lambs had free access to roughage and concentrate feeds. After weaning the lambs were fed so as to promote rapid growth. The lambs suckled by ewes on the low plane did not consume appreciably greater quantities of roughage and concentrate than similar lambs reared by ewes which were adequately fed. Underfeeding of the lactating ewes significantly reduced the body mass of their ewe-lambs at weaning (P = 0,001). The deficit in growth of the lambs was gradually reduced during the post-weaning period, but was still evident at their first parturition.