Melatonin has previously been investigated as a means to mitigate the adverse effects of premature birth or growth restriction in human infants. Supplementing Merino ewes with melatonin during mid to late gestation may also help to reduce the high level of lamb mortality. We aimed to determine the effects of supplementing the maternal environment with melatonin on lamb vitality and survival at birth. From day 80 of gestation, ewes were supplemented with melatonin via a subcutaneous 18 mg Regulin® implant (MEL-IMP n = 13) or 2 mg gel capsule fed orally daily (MEL-FED n = 14). Thirteen ewes received no supplementation (CTL). Ewes were intensively monitored during parturition and rectal temperature and blood glucose measured in lambs (n = 65) at 4 and 24 hours following birth. Survival was measured daily and is continuing to weaning (in August 2018). Preliminary analysis showed there was no difference in the duration of parturition (P=0.334); however, more CLT twin-bearing ewes needed assistance during lambing (CLT=3, MEL-IMP=0; MEL-FED=0. P=0.039), and human intervention for five twin lambs (CTL=4; MEL-IMP=1; MEL-FED=0) was required to ensure survival past eight hours. Rectal temperature was highest in CTL singleton lambs at 4 hours (P=0.050); however, temperature dropped significantly by 24 hours in both singleton and twin CTL lambs (P=0.013). Both MEL-FED (P=0.002) and MEL-IMP (P=0.083) lambs maintained or tended to have increased rectal temperature at 24 hours. While blood glucose was significantly higher in singleton compared to twin lambs at both 4 and 24 hours (4h: P=0.001; 24h: P=0.006), MEL-FED singleton lambs had consistently higher levels of blood glucose compared to other treatments (P=0.003). The latter may be indicative of the lamb’s ability to stand and suckle, and subsequently, a measure of higher colostrum intake during the first day of life.