This paper is the first attempt to use a simultaneous four-equation system to study the role of foreign trade in the analysis of market structure and performance, and the determinants of trade intensity in a newly industrializing country--Taiwan. A cross-sectional analysis is carried out with the manufacturing censuses of 1976. The results indicate that public enterprises significantly influence market structures and performance. Also, import control measures influence import intensity significantly and offset potential impacts of imports on concentration and on profitability. However, trade intensity is mainly explained by comparative advantage rather than market forces (concentration and profitability).