Previous literature indicated that short-term momentum profits hold. This study utilized listed companies in Taiwan stock market from 2002 to 2008 to explore the impact of herd behavior on short-term momentum profits. Empirical results show that the opportunities for investors' applying a momentum strategy in the decreased herd behavior group are better than the opportunities for investors in the increased herd behavior group. Therefore, this study suggests that when the market is crowded with herd behavior, investors should not continue to adhere to the operational logic of a short-term momentum strategy as the literature has suggested. This anomaly is consistent with the theory intuition.