The purpose of this study is to investigate an effective way of using real-time computer-mediated communication (CMC) tools for the development of Korean EFL learners’ oral communicative competence. The subjects of the study are the 53 first-year female university students and they are randomly assigned into three groups: text-, voice-, and video-chatting groups. The major results of the study are as follows: first, all the three synchronous CMC tools are effective in improving the fluency and accuracy of speaking skills. Second, the voice-based CMC tools, not the text-based one, are effective in improving the learners’ interactive skills and active use of communicative strategies. Third, all the three synchronous CMC tools are effective in enhancing the learners’ confidence in their English speaking abilities and beliefs in the improvement of their oral communicative competence. Lastly, the learners’ responses to the use of the CMC tools in performing communicative tasks are very positive in all the three groups. Based on these results, some pedagogical suggestions are made on the effective use of the synchronous CMC tools in Korean English classroom settings.