This paper studies price-matching guarantees in a market where entrant does not have perfect information about incumbent’s cost. The low-cost incumbent can adopt price-matching guarantees as a signal to distinguish itself from the high-cost type and thus effectively deter entry. On the other hand, the high-cost incumbent can successfully fool the potential entrant under certain conditions. Compared with the equilibriums in situations where the option of offering a price guarantee is not available, the use of this instrument either makes it easier for the low-cost incumbent to signal its cost, or expands the range of parameters over which the high-cost incumbent is able to deter entry successfully.