In 1976, 27,766 Seventh-day Adventists answered questions on diet, medications, use of health services, and prevalence of disease. Approximately 55% (n = 15,228) were vegetarians. Compared with vegetarian females, nonvegetarian females reported significantly more overnight hospitalizations and surgeries during the past year and nonvegetarian males reported more overnight hospitalizations and x-rays. The average numbers of chronic diseases were 1.24 in nonvegetarian females and 1.03 in vegetarian females compared with 0.93 and 0.79 in nonvegetarian and vegetarian males, respectively. Nonvegetarian females also reported more chemical allergy (rate ratio (RR) = 1.30), asthma (RR = 1.24), drug allergy (RR = 1.17), beesting allergy (RR = 1.17), and hayfever (RR = 1.15). Only chemical and drug allergy were more prevalent in nonvegetarian males. Medication use was increased by 70-115% in nonvegetarian females and more than doubled in nonvegetarian males. We conclude that a vegetarian diet may decrease the prevalence of chronic disease, medication use, and health service use, and thus, potentially, health care costs.