Applying conventional horizontal merger enforcement rules to mergers of nonprofit hospitals is controversial. Critics contend that the different objective function of not-for-profits entities should mitigate, and possibly eliminate, competitive concerns about mergers involving nonprofit hospitals. We provide evidence relevant to this debate by analyzing ex post a horizontal merger in a concentrated hospital market. Here, the transaction reduced the number of competitors (both nonprofit) in the alleged relevant market from three to two. We find that the transaction resulted in significant price increases; we reject the hypothesis that these price increases reflect higher post-merger quality. This study should help policymakers assess the validity of current merger enforcement rules, especially as they apply to not-for-profit enterprises.