A nationwide mail survey was used to determine the degree to which primary-care physicians indicated that they practice the "core competencies" in clinical nutrition identified by Young et al (Am J Clin Nutr 1983;38:800-10). We also surveyed the nutrition-related attitudes of these physicians. Although the 3416 physicians who responded to the survey tended to report favorable attitudes toward using nutrition in their practice, these favorable attitudes were not consistent with their own reports of clinical performance. Neither the positive- or negative-attitude score correlated highly with the reported behavior-practice score. The clinical practices reported by those surveyed are well below the minimum level defined by the Young et al essential core competencies in clinical nutrition. The attitudes, practices, and demographic characteristics associated with the clinical performance variables suggest educational strategies for improving the competence of primary-care physicians and medical students in clinical nutrition.