Although health departments routinely inspect restaurants to assess compliance with established hygienic standards, few data are available on the effectiveness of these efforts in preventing foodborne disease. The study reported here assessed the impact on foodborne-disease hospitalizations in Los Angeles County of a restaurant hygiene grading system that utilized publicly posted grade cards. The grading systm was introduced in January 1998. Hospital discharge data on foodborne-disease hospitalizations were analyzed for Los Angeles County and, as a control, for the rest of California during the period 1993-2000. Ordinary least-squares regression analysis was done to measure the effect of the grading progam on these hospitalizations. After baseline temporal and geographic trends were adjusted for, the restaurant hygiene grading program was associated with a 13.1 percent decrease (p < .01) in the number of foodborne-disease hospitalizations in Los Angeles County in the year following implementation the program (1998). This decrease was sustained over the next two years (1999-2000). The results suggest that restaurant hygiene grading with public posting of results is an effective intervention for reducing the burden of foodborne disease.