This study examines the foreign currency derivatives trading of KOSDAQ firms and analyses the relations of derivatives trading and foreign exchange rate exposure in the period 2005~2010. The amount of derivatives trading reaches 27.7% of total assets for the trading firms before global financial crisis period (2005~2007). While, the amount decreases to 17.6% of total assets during the crisis period (2008~2010). These amounts are much greater than those of KOSPI firms which are calculated using similar data specification and periods. The variables which are usually adopted as determinants of derivatives trading do not explain the usage of derivatives in the analysis of period 2005~2007. These results suggest that KOSDAQ firms use derivatives not only foreign exchange risk managements but also trading purposes during this period. Test results do not show sufficient evidence that KOSDAQ firms use derivatives trading in an effective manner to manage foreign exchange rate exposure. In sum, test results suggest that to achieve the goal of managing foreign exchange rate exposure firms should estimate their open position in foreign currency properly before conducting foreign currency derivatives trading.