The current research tested the priming effects of online comments’ valance, appeals, and degree of reader-involvements on readers’ attitude of the products, evaluations of the companies, and recommendation likelihood of the brands. A control group was presented with news stories only. Results indicated that preceding comments primed the valence and appeals of participants’ self-generated comments. Comments valence biased participant’s immediate attitude, evaluation, and recommendation likelihood toward the direction that consistent with the comments they read. In addition, an interaction effect was found among comments valence, appeals, and degree of involvements; emotional comments indicated a greater priming effect than rational comments did only in the negative valence group. The priming effects were illustrated not only in perceptions, but also the details of participants’ own comments.