Little has been reported on the determinants of performances of affiliates of small and medium-size multinational enterprises (MNEs) in developing countries. The paper"s research objective is to identify determinants of performances of Korean affiliates of small and medium-size MNEs in Korea. The sample is a group of 38 Korean subsidiaries of small and medium-size MNEs. Six hypotheses were formulated and tested. The findings are in the following. First, performances of Korean affiliates of small and medium-size MNEs were influenced significantly by the degrees of levels of control and commitment from parent firms and the proportion of exporting in the affiliates. However, age, size, and technology level are not significantly related to the performance of affiliates of small and medium-size MNEs in Korea. However, nationality and industry composition of the sample are found not to affect performance significantly in the Korean affiliates of small and medium-size MNEs.