Ｉｎｏｔｇｙ＆ Ｓｏｙｙｏｔｍ＆ Ｍｏｘｒｙ＆ ｏｔ＆ ｚｎｋ＆ Ｚｎｘｋｋ＆ Ｊｋｉｇｊｋｙ＆ ｌｘｕｓ＆ ７？＞６＆ ｚｕ＆ ８６７６０ 1 Quanbao Jiang Xi’an Jiaotong University, China Shuzhuo Li Xi’an Jiaotong University, China Marcus W. Feldman Stanford University, USA Ｇｈｙｚｘｇｉｚ The strictly implemented fertility policy that has been in force in China since 1980 has led to a continuously increasing sex ratio at birth and in turn to a large number of missing girls. Based on China’s four recent censuses, we find that the number of missing girls accounted for 2.93 percent of all girls expected to have been born during 1980 to 1989, 9.31 percent during 1990 to 1999, and 10.85 per- cent during 2000 to 2010. The 1980– 2010 birth cohorts have 20 million missing girls, namely 7.34 percent. For cohorts born from 1980 to 2010, males outnumber females by 36 million at the census times, 20 million as a result of the phenomen- on of missing girls, while the remaining 16 million is biologically determined, as there are about 5 percent more male births under normal sex ratio at birth. We discuss possible adjustment of the fertility policy in China and measures that might lead to a more normal sex ratio at birth. Ｑｋ｡＆ ｝ｕｘｊｙ Missing girls, sex ratio at birth, excess female mortality, life table Introduction The stringent family system of patrilineality, patriarchy, and patrilo- cality throughout Chinese history has resulted in a strong preference for sons and discrimination against girls in childbearing and child rearing * This work is supported by the project of the National Social Science Foundation of China (09XSH005), and the 985-3 project of Xi’an Jiaotong University.