A system for reporting dietary data in terms of food groups is described. The scheme was developed jointly by the National Heart, Lung, and Blood Institute (NHLBI) and the U.S. Department of Agriculture to identify food use patterns in various population groups. The system comprises 14 major groups and 75 minor groups based on major nutrient composition with special attention to fats. One-day dietary recalls from 5,640 participants in the Lipid Research Clinics (LRC) Prevalence Study were analyzed to determine the frequency of food group usage by males and females in age groups 6 to 9, 10 to 19, 20 to 59, and 60 and older. Food group use is reported as percent of the population reporting use as obtained by the dietary recall as well as the average number of times each food group was mentioned by the users. LRC food selection patterns are compared with the Dietary Guidelines. Findings in this report indicate that, for the LRC population, some of the foods emphasized in the guidelines are not eaten with a high degree of frequency.