Background Neck circumference (NC) is associated with metabolic syndrome (MetS) in the general population. It is not known if NC is associated with MetS and subclinical atherosclerosis in retired National Football League (NFL) players. Hypothesis We hypothesized that NC is associated with MetS and subclinical atherosclerosis (assessed as coronary artery calcium [CAC] and carotid artery plaque [CAP]) in retired NFL players. Methods NC was measured midway between the midcervical spine and midanterior neck in 845 retired NFL players. CAC presence was defined as total CAC score >0. CAP was defined as carotid plaque of at least 50% greater than that of the surrounding vessel wall, with a minimal thickness of at least 1.2 mm on carotid ultrasound. Logistic regression analysis was used for the association of NC with CAC or CAP. Results Of the participants, 21% had MetS. CAC and CAP were present in 62% and 56%, respectively. Those with MetS had a higher median NC than those without MetS (17 vs 16 inches, P < 0.0001). NC was not associated with the presence of CAC or CAP in an unadjusted model and after adjusting for age, race, and cardiometabolic risk factors (odds ratio [OR]: 1.11, 95% confidence interval [CI]: 0.94-1.31 for CAC; OR: 0.96, 95% CI: 0.82-1.12 for CAP per 1-standard deviation increase in NC [3.8 inches]). The results were similar when the predictor variable was NC indexed to body mass index. Conclusions In retired NFL players with a high prevalence of CAC and CAP, NC was not associated with coronary or carotid subclinical atherosclerosis. NC may not be the most appropriate risk marker for atherosclerosis.