In a community hepatitis A outbreak in the Rochester, New York area, 64 of 79 (81 %) people with anti-hepatitis A 1gM-antibodies and onset of symptoms from 9 April–31 May 1994, recalled eating food obtained from a retail buyer's club. Eleven (65%) of 17 households with cases contained club members compared with 7 (21%) of 34 neighbourhood-matched control-households (matched odds ratio 8·5; 95% CI 1·7–41·6). Club employees who ate sugar-glazed baked goods were at fourfold increased risk for hepatitis. The source of infection was an 1gM- positive baker who contaminated baked goods while applying sugar glaze. Computer-generated purchase lists implicated 11–12 March and 21–24 March as the most likely dates when contamination occurred. This investigation demonstrates the importance of food workers adhering to established hygiene practices. Computer-generated commercial datasets can be useful in epidemiologic investigations.