OBJECTIVE: To describe and identify the causes of an outbreak of Salmonella enteritidis gastroenteritis that took place in June 1998, among tertiary care hospital workers, in Mexico City. MATERIAL AND METHODS: Cases were hospital workers who developed diarrhea or fever associated with gastrointestinal symptoms, after a meal at the hospital's dining room on June eight; controls were asymptomatic employees who also ate at the hospital's dining room on the same day. A food questionnaire was applied, and stool samples were obtained from all study subjects, including kitchen personnel. Blood cultures were practiced for febrile patients. Odds ratios with 95% confidence intervals (95% CI) and the chi-squared were used for statistical analysis. Statistical significance was set at p < 0.05. RESULTS: One-hundred-fifty-five workers developed symptoms, but only 129 (83.2%) answered the questionnaire; 150 controls were also studied. The most common symptoms were diarrhea (85%), abdominal pain (84%), cephalea (81.4%), nausea (78.3%), and chills (74.4%). Eight blood cultures were negative; 59 stool cultures (46%) from cases and six (4%) from controls, were positive for Salmonella enteritidis. Egg-covered meat was the suspected source of infection (OR 19.39, 95% CI 9.09-41.4); some other foodstuffs like fruit dessert and yogurt, were significantly more frequent in cases than in controls. Food cultures were all negative. CONCLUSION: This outbreak was probably caused by Salmonella-contaminated foodstuffs (egg-covered meat with potatoes) due to deficient cooking. This report shows the importance of food-quality programs for hospital meals.