Antitrust scholars and industrial organization economists have long been interested in analyzing the competitive effects of mergers between competitors. Much of the attention devoted to this subject has focused on the correlation between the concentration in a market and its prices. The traditional analysis suggests that higher levels, of concentration lead to higher prices as a single firm gains market power or as leading firms are able to engage in stable, tacitly collusive agreements because of the smaller number of firms. In grocery retail, for example, a myriad of studies comparing the concentration levels in different cities and the prices in those cities have found strong positive relationships between market concentration and price. Findings such as these have justified an active antimerger policy in grocery retail, exemplified in Los Angeles recently by the order that Albertson's divest 145 stores as a condition of its merger with American Stores. The prevalent antimerger policy in Los Angeles has its roots in the 1966 United States v. Von's Grocery Co. decision, which prohibited the merger of two grocery chains that would control less than 9 percent of a post-merger market characterized by remarkably low concentration levels. This Comment shows that the empirical studies in the grocery retailing industry, which find a positive relationship between concentration and price, are not a reliable basis for policymaking decisions by administrative agencies and the courts. It further illustrates that the reasoning behind the Von's Grocery decision is not only flawed and incorrect, but is also damaging to current merger doctrine that has developed into an otherwise coherent framework for analyzing the competitive effects of horizontal mergers. Time series analysis of concentration and price levels in the Los Angeles market indicates that the relationship between concentration and price, up to current levels of market concentration, has been negative, not positive as indicated by previous cross-sectional research. Elimination of decisions such as Von's Grocery from current merger doctrine will prove beneficial for judges, and more importantly, for consumers. Finally, this Comment argues that including reliable empirical studies of the relationship between concentration and price across different industries of antitrust concern can complement the in-depth analysis that the Merger Guidelines lay out for the U.S. Department of Justice and the Federal Trade Commission antitrust officials. Doing so would allow for a more subtle and complete understanding of how concentration levels have affected prices in the past and how likely they are to do so in the future.