Little is known about the variables that account for why parents underestimate the pain of their child. In the present experiment, the joint impact of parental catastrophizing about their child's pain and children's facial pain expressions was examined upon pain estimates of their child undergoing a pressure pain test. In line with previous research, parents underestimated their children's pain. Interestingly, it was found that pain was estimated as higher when the child showed more facial pain expressions and when parents catastrophized more about their child's pain. An intriguing finding was that catastrophizing about their child's pain was related to less parent-child incongruence in pain ratings. The discussion addresses the possible functions of catastrophizing of parents about their children's pain, and delineates avenues for future research.