The objective of this investigation is to use the health belief model (HBM) to explain the percentage of calories from fat in the diet (PCF) for marital partners. The model includes four sets of determinate variables: perceived threat of a high-fat diet, barriers to a healthier diet, food choices made for health reasons, and self-efficacy, as well as sociodemographic background factors. One hundred fifty-five married couples were selected by a random area sample from the state of Iowa. Husbands and wives were interviewed separately in the home. The results partially support the HBM as applied to a nutrition domain and revealed interesting gender differences. For wives the cost of healthy diet changes had an effect on PCF. For husbands, perceived threat and self-efficacy had an effect on PCF. The differences are discussed on the basis of gender roles in the home and gender socialization.