Geographic market definition has been, and remains today, the key battleground on which hospital merger cases are won or lost. This article, published in The Antirust Source, reviews the FTC v. Advocate litigation, the Seventh Circuit opinion, and the state of hospital merger geographic market definition in the case’s wake. While the authors, Steven Tenn and Sophia Vandergrift, focus on geographic market definition, many of the issues they discuss similarly arise in the context of competitive effects analysis.