We investigate the causes of the high first day returns of Chinese firms making an initial public offering (IPO) of A-shares from 1991 to 2003 on Shanghai and Shenzhen stock exchanges. Our results show an average underpricing of 175.21 percent. We argue that the IPO underpricing is an interaction of ex-market underpricing and on-market overpricing. The high first day returns of China’s IPOs are most likely generated from on-market overpricing. Government intervention, market speculation, special ownership structure, strategy of proceeds maximization and risk concerns are the main drivers of the high first day returns. However, the high first day returns have decreased significantly in recent years. We explained this change by testing the risk composition hypothesis, the realignment of incentives hypothesis and the changing issuer objective hypothesis, which shows that the reduction in risk, senior managerial shares and seasoned offerings mitigate the first day returns.