Since its inception in 2002, the private placement system has become one of the important alternatives for the listed and OTC companies in Taiwan to raise needed capitals. The purpose of the study is to investigate the declaration effect and one-year stock returns of the private placement companies and to examine if the companies would engage in earnings management before undertaking the private placement. Empirical results indicate that for the companies that decided to undertake the private placement, there was no significant declaration effect; the cumulative abnormal returns after one year of the private placement have been significantly positive. In addition, the study also found that the more insiders and institutional investors participated in the private placement, the higher the long-term cumulative abnormal returns and company size and market-to-book ratio are both negatively related to long-term cumulative abnormal returns. However, there is no evidence that the companies had conducted earnings management to influence specific investors to participate in the private placement.