OBJECTIVE To identify important food sources and estimate dietary intake of vitamin K-1 (phylloquinone) in the American diet. METHODS Core foods from the US Food and Drug Administration (FDA) Total Diet Study (TDS), which was based on the 1987-88 Nationwide Food Consumption Survey (NFCS), were analyzed for vitamin K-1. These nutrient values were then applied to the FDA TDS consumption model. METHODS Of the NFCS participants within the 14 selected age-gender groups, 3,634 who had 3 days of dietary data were included in the FDA TDS consumption model. METHODS Vitamin K-1 intakes were estimated for each of the age-gender groups; the percentage contribution of each food item to total intake of vitamin K-1 was calculated from the FDA TDS model. RESULTS Of the 14 age-gender groups selected, the 25- to 30-year-old women and men consumed less than the current Recommended Dietary Allowance (RDA) for vitamin K. In contrast, formula-fed infants had estimated vitamin K-1 intakes six times greater than the RDA. All other groups consumed amounts within the recommended daily intakes but lower than 90 micrograms/day. The top contributors to total vitamin K-1 intake were dark-green vegetables, although the fats and oils added to mixed dishes and desserts were also important contributors. The proportion of vitamin K-1 obtained from vegetables increased with age. CONCLUSIONS The data identify important dietary sources of vitamin K-1 in the American diet. This knowledge can be used to develop dietary assessment instruments for use in epidemiologic studies.