Objectives: The purpose of this study is to define and clarify the causes of differences in physique between urban students and rural students in China.Methods: Subjects are 2,524 students (male, 838; female, 1686) who entered K University in Shanghai in September, 2001. The data used in this study is based upon K university's Yearly Health Check Record and Students' Family Condition Record. Correlation analysis, analysis of variance (ANOVA) and analysis of covariance (ANCOVA) were applied to analyze the relationships between physique and gross family income, family income per capita, latitude, air temperature, precipitation or altitude.Results: Urban students' height and weight are significantly greater than rural students' in both males and females. Both male students and female students are significantly taller and heavier in accordance with per capita increases in students' family income. The height and weight of male and female students whose parents are peasant farmers are least. With regard to the relationship between physique and urban-rural factors, the F value decreases clearly when family income per capita is taken as a covariate, while the F values slightly decrease also when factors of latitude etc. are taken as covariates. The main cause of differing family income is occupational difference between urban areas and rural ones.Conclusion: Students born in urban areas are taller and heavier than those born in rural areas. The main cause of these differences is family income per capita. The main cause of variations in family income is the income difference in occupations.