['Despite concerted scientific, educational, and congressional calls to increase nutrition coverage in medicine for more than half a century, most graduating medical students report an inadequate quality and quantity of nutrition training. Furthermore, practicing physicians report a lack of confidence and related proficiency in nutrition counseling skills because of inadequate training. Assessment of nutrition proficiency and related training of practicing physicians may support the prioritization of nutrition topics to be included in medical education.', 'We tested the hypothesis that the perceived adequacy of nutrition training (quality and quantity) of family physicians in Washington State is positively correlated with self-reported nutrition proficiency in 5 nutrition factors determined after confirmatory factor analysis.', 'A randomized mail survey method (n = 778 possible respondents), which involved one mass-mailing follow-up, was used.', 'A 39.3% response rate was achieved (n = 306 respondents). The 31-item questionnaire was reduced to 5 factors, explaining 48.5% of the total variance (alpha = 0.916). Perceived quality (poor to excellent) of nutrition training was positively correlated with self-reported nutrition proficiency scores for all 5 factors (P < 0.01). No significant differences were noted between zip code or sex and mean nutrition proficiency scores for all 5 factors.'] Is self-reported nutrition proficiency positively correlated with the perceived quality of nutrition training of family physicians in Washington State?