To investigate the hypothesis that misreporting observed in dietary assessments would be associated with nutrition knowledge and health consciousness, we compared the degree of misreporting between 99 female dietitians and 117 nondietitians who worked at welfare facilities in Japan. Sodium, potassium, and protein intake were assessed by two 24-hour urine collections, 4-day semiweighed dietary records, and 2 validated diet history questionnaires. Intake of these 3 nutrients measured by each method was compared. The ratio of self-reported intake to biomarker-based intake was used as an index of reporting accuracy and compared between dietitians and nondietitians. Correlation coefficients between biomarker-based and self-reported intakes were also compared between dietary assessment methods within the same group, as well as between the 2 groups. The dietitians tended to underreport sodium and protein intake more severely than the nondietitians and overreported potassium intake more obviously. However, the degree of misreporting did not significantly differ between the 2 groups. The correlation coefficients between biomarker-based and self-reported intakes were significantly lower with the 2 diet history questionnaires than with the diet record, particularly in the dietitians. In conclusion, misreporting was strongly suspected to be more severe among the dietitians, and the validity of the diet history questionnaires differed between the 2 groups and this result suggests that misreporting might be associated with higher nutrition knowledge and health consciousness.