||Mass media and market participants claimed that hedge funds established highly speculative positions on the ASEAN currencies, especially on Thai baht during the Asian Financial Crisis, while researches or reports from the IMF and the FSF, which were conducted by professionals, including Eichengreen, alleged that hedge funds played only a limited role during the crisis. Their researches typically focused only on large hedge funds. This paper examines the potential market impacts of hedge funds on the emerging markets during the selected financial crises in the 90s, specifically the Mexico Peso Crisis of 1994 and the Asian Financial Crisis of 1997, by including both large hedge funds and small hedge funds. In this paper I will show, by including small hedge funds in the analysis that, hedge fund did play significant roles in the financial crises. In the Asian Financial Crisis, hedge fund appeared to act as a destructive role to Thai baht while a supportive role to Indonesia rupiah, in which the result is in line with the consensus of the market participants. I will also examine the behavioral differences between large and small hedge funds during the crises. In addition to these, this paper shows that the exposure of hedge fund had changed significantly during the crises and there were also considerable behavioral differences between large and small hedge funds.