This study used published relative risk estimates for birth defects, premature birth, and coronary heart disease associated with vitamin intake to project potential annual cost reductions in U.S. hospitalization charges. Epidemiological and intervention studies with relative risk estimates were identified via MEDLINE. Preventable fraction estimates were derived from data on the percentage of at-risk Americans with daily vitamin intake levels lower than those associated with disease risk reduction. Hospitalization rates were obtained from the 1992 National Hospital Discharge Survey. Charge data from the 1993 California Hospital Discharge Survey were adjusted to 1995 national charges using the medical component of the Consumer Price Index. Based on published risk reductions, annual hospital charges for birth defects, low-birth-weight premature births, and coronary heart disease could be reduced by about 40, 60, and 38%, respectively. For the conditions studied, nearly $20 billion in hospital charges were potentially avoidable with daily use of folic acid and zinc-containing multivitamins by all women of childbearing age and daily vitamin E supplementation by those over 50.