This study attempts to examine the factors affecting the introduction of e-Business systems and also, to assess the effects of various e-Business systems on firm performance. Empirical analysis is carried out with firm data of 2009, which is collected from Firm Activity Survey of Statistics Korea. Firm performance is measured by four indexes; operating income per employee, value added per employee, return on assets, and return on sales. Empirical results indicate that a firm is more likely to introduce any e-Business system as its size and its assets per employee are larger and as its ratio of labor compensations to operating costs is lower. Additionally, a firm with higher skill levels and more fruitful management experiences is more likely to have any e-Business system. In general, it appears that the presence of e-Business, especially enterprise resources planning, has positive effects on the firm performance.