The influence of perennial ryegrass endophyte on sheep reproduction and early lamb growth was studied in a 3-year grazing experiment at the AgResearch regional station at Gore (46”07’S, 168”54’E). The trial consisted of 8 paddocks sown in endophyte-infected (+E) or endophyte-free (-E) Grasslands Nui perennial ryegrass, with (+C) or without Grasslands Huia white clover. Endophyteinfected ryegrass delayed the lamb drop and reduced lamb weight gains during the lactation period. Lamb drop was delayed by an average of 3-5 days especially in the presence of clover. This may be due to an extended gestation period or delayed mating. There was no effect of endophyte on lamb birth weight, ewe conception rate and liveweight changes over autumn, winter and spring.