Survey evidence suggests that many U.S. and European consumers do not spend a lot of time comparing mortgage products. We show, however, that mortgage shopping is associated with a substantial monetary payoff, using a unique data set from a website where borrowers (not the lenders) can post their complete set of received mortgage rate offers. A borrower who shops for five mortgage offers is able to save 7,078 euros in net present value on average. The potential savings suggest suboptimal mortgage shopping as the opportunity cost of time to renegotiate additional quotes is unlikely to be that high.