Maintaining pregnant ewes with a body condition score (BCS) of 3.0-3.3 during late gestation is critical as it can strongly influence peri- and post-partum lamb viability, growth and survival (Hinch and Brien 2014; Kenyon et al. 2014). This study determined whether the BCS of 96 twin-bearing Merino ewes at approximately d123 of gestation would influence live weight (LW) and survival of their lambs at birth, marking and weaning. The effects of ewe BCS on lamb survival was determined using a chi-square test and an ANOVA was conducted to determine the impact of BCS on lamb LW. Ewe BCS group had no effect on lamb LW at birth (P = 0.322). At marking, lambs born to ewes in the BCS ≤2.5 group tended to be lighter than lambs born to BCS 3.0 and 3.5 ewes (P = 0.071), with these lambs being lighter at weaning than lambs born to BCS 3.0 and 3.5 group ewes (P = 0.044). Twin lamb cumulative survival rates were unaffected by ewe BCS group (P > 0.05). This study demonstrated that twin-bearing ewes with a BCS of ≤2.5 reared lighter lambs at weaning than BCS 3.0 and 3.5 group ewes. Ewe BCS and fat levels are positively related to milk production (Gibb and Treacher 1982). It is, therefore, suggested that ewes with a BCS of ≤2.5 had less body fat to mobilise which may have negatively impacted their lactation performance and consequently the growth of their offspring. As such, it is not surprising that they weaned lighter lambs; however, it is interesting that this did not impact lamb survival from birth to weaning. In conclusion, these findings indicate that farmers should ensure that twin-bearing ewes maintain a BCS of above 2.5 during late gestation in order to maximise lamb growth and safeguard survival to weaning.