ABSTRACT. The effect of shearing ewes at 50 days of gestation on birth and weaning weight, vigour of the lambs in the first hour of life and the survival of single and twin lambs was investigated. Ultrasound pregnancy diagnosis was used to allocate 140 Polwarth ewes on Day 50 of gestation to one of four treatments, including two factors:shearing time (prepartum (PS) and postpartum (U)) and litter size (single (S) and twin (T)) resulting in the following treatments:single-bearing ewes shorn at 50 days of gestation (SPS, n = 39), single-bearing ewes unshorn (SU, n = 40), twin-bearing ewes shorn at 50 days of gestation (TPS, n = 28) and twin-bearing ewes unshorn (TU, n = 33). All ewes grazed together on improved pastures. Body condition score of the ewes was recorded once every 2 weeks from shearing until weaning, and plasma concentration of NEFA in ewes was measured once every 2 weeks from Day 30 postpartum until weaning (Day 104 ± 7). Gestation length, lamb behaviour during the first hour of life, lamb weight at birth and daily weight gain from birth to weaning and lamb survival were measured. Ewe body condition and plasma non-esterified fatty acids concentration was not affected by shearing time or litter size. Birthweight of the lambs was affected by shearing time (P = 0.0002), litter size (P