Gamers use avatars to represent themselves to interact with others in online games. However, gamers’ behavior via avatars has received insufficiently attention by electronic commerce scholars, warranting further study on this issue. Positive interactions among online gamers should foster their loyalty to the game. Therefore, this study investigated how avatar design affects gamers’ behavior via avatars. This study obtained responses from more than one thousand online gamers that were used for further analyses. Criteria were set to exclude some invalid responses, so as to increase data validity. Moreover, reliability and validity were checked by using six tests, demonstrating the adequate performance in psychometric properties. Structural equation modeling was conducted for analyses. This study found that avatar design has an important impact on gamers’ behavior via avatars. Specifically, positive perceptions on avatar design motivate the gamers to exhibit positive behavior via avatars. Findings of this study provide feasible means for electronic commerce managers to encourage gamers’ positive interactions and thus should create strong virtual communities and subsequently loyal gamers