One of the Millennium Development Goals is to ensure universal access to primary education by 2015. However, primary school dropout remains a challenge in many developing countries. While official statistics in China report aggregated primary school dropout of only 0.2%, almost no independent, survey-based studies have sought to verify these dropout rates in rural areas. The primary objective of our study is to document the dropout rate in primary schools in rural China and compare the dropout rate of ethnic minorities and Han students. Using a first-hand dataset of 14,761 primary students in northwest China, we demonstrate that the annual dropout rate in poor rural areas is 2.5%, suggesting a cumulative dropout of 8.2%. Importantly, Hui and Salar minority students drop out at rates that are significantly higher than the official rates. Most noteworthy, 23% of Hui girls and 22% of Salar girls are dropping out by the end of grade 6. Our findings call for more attention to China's primary school dropout issue--especially in minority areas. Policymakers should begin to examine new ways to increase the chances for minority students to succeed in the educational system.