This study tries to set up a simultaneous equation model to measure the cause-and-effect of the market structure, conduct and performance of Taiwanese fruit-export industry. Based on the emprical results, it is to identify the sources of profitability. The results, in general, have indicated that the profitability of their industry is caused most by firm's monopoly power than by its operational efficiency. However, the effects of firm's operational efficiency on their profitabilities are still important. The evidences for these results show that it is not always true since the excess profits for some firms are treated as the consequences of their monopoly power only.