Using initial public offerings of 512 UK companies newly admitted to London Stock Exchange between 1985 and 1990, we explored the reason of underpricing of new issues. We particularly examined the underpricing of new issues in terms of signalling hypothesis.  We found that there is a positive relationship between the value of the issuing firms and the fraction of equity retained by entrepreneurs. This finding is consistent with Leland and Pyle`s model(1977) and the evidence of Downes and Heinkel(1982). We also found a positive association between the firm value and the degree of underpricing. In addition, our empirical evidence revealed that the underpricing of the UK IPOs is positively related to the fraction of equity retained by the original shareholders. Thus, our results support Grinblatt and Hwang`s model(1989) which predicts a positive relationship between the value of firm and the degree of underpricing