In December 2002, the Ohio Department of Health was notified of two children with Salmonella infection. Both had a history of drinking raw milk from a combination dairy-restaurant-petting zoo (dairy). The dairy was the only establishment in Ohio licensed to sell raw milk and reported 1.35 million visitors annually. We investigated to determine the extent of the outbreak and identify illness risk factors. A case patient was any person with pulsed-field gel electrophoresis-matched Salmonella enterica serotype Typhimurium from 30 November 2002 to 18 February 2003. Sixty-two met the confirmed case definition. Forty dairy case patient patrons were included in a case-control study; 56 controls were their well meal companions. Consumption of raw milk was found to be associated with illness (odds ratio, 45.1; 95% confidence interval, 8.8 to 311.9). The dairy discontinued selling raw milk. Because 27 other states still allow the sale of raw milk, awareness of the hazards of its consumption should be raised and relevant regulations carefully reviewed.