Technical Abstract: Rain use efficiency (RUE), commonly described as the ratio of aboveground net primary production (ANPP) to mean annual precipitation (MAP), is a critical indicator for predicting potential responses of grassland ecosystems to changing precipitation regimes. However, current understanding on patterns and controls of RUE is primarily derived from temperate grasslands, and little is known about alpine grasslands. In this study, we examined RUE in the Tibetan alpine grasslands across a precipitation gradient using biomass measurements from 675 plots and soil physical and chemical properties from 405 soil profiles obtained from a regional biomass and soil survey across the plateau during 2001-2004. Our results showed that RUE in alpine steppe was significantly lower than in alpine meadow. The different RUE in these two grassland types were largely induced by their differences in species richness, soil texture, and soil carbon content. RUE exhibited an initial increase in alpine steppe and a subsequent decrease in alpine meadow along the precipitation gradient, suggesting that alpine steppe and meadow may respond differently to the alteration in precipitation patterns.