Endophytes are fungi that form inapparent infection within leaves and stems of healthy plants. En2dophytes or endophytic fungi exist widely in the higher plants and are generally considered as mutual symbiotes to the host plants. The present study examined the association of an endophyte (Neotyphodium lolii) with its host plant, Lolium perenne cv. Pinnacle. Both endophyte status and drought stress level were considered. En-dophyte-free (EF) plants were obtained by a mild heat treatment while endophyte-infected (EI) plants were germinated directly. After transplantation and four weeks of growth in pots, EF and EI plants were subjected to drought stress of different water status in the soil; soil moisture was maintained at 20% to 40%, 40% to 60%, 60% to 80%, and over 80% of the field capacity. Leaf extension rate and tiller numbers were mea-sured during drought stress, and biomass was determined after recovery stage. Our objective was to determine the influence of endophyte infection on growth characteristics and drought resistance of the host plants. Leaf extension of Lolium perenne shifted during drought stress, while no significant superiority was found in EI plants as compared with EF plants. The EI plants tended to produce more tillers than the EF plants dur-ing drought stress. After severe stress and recovery stage, the EI populations had a significantly higher root/shoot ratio than the EF populations, while there was no significant difference in total biomass between EI and EF populations. Our results indicated that endophyte infection might enhance the drought resistance of the host plant by enhancing its tiller production during drought stress and its photosynthate allocation to roots between stress periods.