Three are three dominant ways in which the relation of gratitude is described in moral philosophy - as a debt, as an appropriate emotion or as a virtue. Although the debt theory is coherent and clear, it must be complemented with a psychological account of the relation between the giver and the recipient of a favor. A virtue based account of gratitude in turn moves the limits of what is morally significant too far. The conditions under which one is obliged to express gratitude comprise both motives of the giver and the recipient and the circumstances in which the favor was done. Egoistic motivation, coercion or lack of intentionality in the initial act of favor make it impossible to talk about the recipient's obligations. One should also exercise caution in the use of the idea of claim or right to gratitude.