There are three purposes of this study. First, this study examines whether any change in 12b-1 fees (marketing fees) will influence mutual fund cash inflows. Second, this study examines whether the sensitivity of fund inflows to change in 12b-1 fees will be influenced by investors with different degrees of sophistication. Investors with high degree of sensitivity to performance are deemed as sophisticated investors in this study. Third, this study investigates whether flow-to-performance sensitivity will be influenced by investors’ personality traits that is, investors with external locus of control versus investors with internal locus of control. The empirical results show that any positive change in 12b-1 will lead to a significant increase in fund flows. In addition, the sensitivity of fund inflows to change in 12b-1 fees will be lower for sophisticated investors, which is proxy by investors with high degree of sensitivity to fund return performance. Finally, this study finds that investors with external locus of control tend to have lower sensitivity to mutual fund performance.