This paper studies how the labor union strength affects the repurchase decision. We argue that a low (high) unionized firm is more (less) likely to buy back shares. The low unionized firm may buy back more shares because of the wealth transfer effect between shareholders and labors. In addition, the high unionized firm may not buy back shares to avoid infuriating the powerful union. Yet, we also find that, once the high unionized repurchaser decides to buy back shares, the firm will complete the repurchase program against the labor union. Therefore, a negative relation between the post-buyback abnormal return and the extent to the unionization is suggested. Finally, we find that the impact of union on the repurchase decision is reduced if the buyback is associated with the mergers or employee stock options, and impact is increased whenever the buyback is related to the excess cash distribution or the corporate governance of the firm is well.