Beer consumption is commonly an issue in a medico-legal setting, requiring estimates either of a likely blood alcohol concentration (BAC) for a given pattern of consumption or vice versa. The current study found considerable variability in the alcoholic strength of the beverages tested, even within the same class. Overall, the range of concentrations was 2.92 percent v/v to 15.66 percent v/v. The mean alcohol concentration for ales was 5.51 percent v/v (SD 1.23 percent v/v), and for lagers, 5.32 percent (SD 1.43 percent v/v). Some specialty brews had characteristically higher or lower mean concentrations; ice beers, 6.07 percent v/v; malt liquor, 7.23 percent v/v; light beer, 4.13 percent v/v; and seasonal ales, 6.30 percent v/v. Six brands of lager and four light beers account for the majority of all beer sales in the United States, and the mean alcohol concentration for these products was measured as 4.73 percent v/v and 4.10 percent v/v, respectively. Few of the beers (17 percent) were labeled with respect to alcohol content, and in some cases, there was a significant disparity between the concentration listed on the label and the measured alcohol concentration. The authors advise that toxicologists should exercise caution when performing Widmark type calculations, using all available information to select the most appropriate estimate for alcoholic strength of a beer or malt beverage. 1 figure, 2 tables, and 20 references