This study was designed primarily to examine how synchronous communication facilitated graduate students' online collaboration and their perceptions of synchronous communication. Thirty online graduate students were required to use instant messenger (IM) to discuss their group projects and later post their reflections on their collaboration. The result of content analysis of the IM transcripts revealed that the collaborative interactions in face-to-face situations could be identified in students' online collaboration. Students' reflections showed that they deemed it as a positive and productive experience despite some scheduling and technical issues. Suggestions are provided for the design and implementation of synchronous communication for successful online collaboration. (Contains 2 tables.)