The purpose of this study is to evaluate the management efficiency of professional teams in the Korean Baseball Organization by using Data Envelopment Analysis (DEA). The professional baseball teams in Korea are in urgent need of efficient management as no teams are making profits and their financial deficits are growing. DEA is a technique to measure relative efficiency when coping with multiple inputs and multiple outputs. We implemented total player salary as input item and winning percent and total fan attendance as output items to evaluate 8 teams' management efficiency for the 2004 season. The analysis identified teams operating relatively efficient and teams that are not efficient. The result revealed that a teams' efficiency score is not necessarily correlated to the final standings in the league. Rather, teams that are relatively mediocre sized outperformed the teams well-known for their financial abundance.