Aim: Oxytocin regulates food intake, carbohydrate and lipid metabolism, and urinary sodium excretion. We assessed the association between serum oxytocin levels and presence of metabolic syndrome (MetS) in older men. Methods: Cross-sectional study was performed in 540 volunteer men aged 50-85 yrs from the MINOS cohort. Oxytocin was measured in fasting serum by radioimmunoassay (Oxytocin RIA, Phoenix Pharmaceuticals). MetS was diagnosed using the harmonized definition. Results: Serum oxytocin was higher in 166 men with MetS vs. controls (p < 0.005). After adjustment for confounders including leptin, higher oxytocin was associated with higher odds of MetS (OR = 1.38 per SD, 95% CI: 1.10-1.71, p0.74 pg/mL (median) had higher odds of MetS vs. men with oxytocin 60.74 pg/mL (OR = 2.06, 95% CI: 1.33-3.18, p0.74 pg/mL and total testosterone < 300 ng/dL (< 10.4 nmol/L) had higher odds of MetS vs. men without these characteristics (OR = 3.95, 95% CI: 1.65-9.46, p < 0.005). Men having 25-hydroxycholecalciferol levels0.74 pg/mL had higher odds of MetS vs. men without these characteristics (OR = 2.86, 95% CI: 1.47-5.58, p0.74 pg/mL and osteocalcin levels < 14.6 ng/mL (lowest quartile) had higher odds of MetS vs. men without these characteristics (OR = 4.12, 95% CI: 2.07-8.20, p < 0.001). Conclusion: In older men, higher serum oxytocin levels are associated with higher odds of MetS regardless of potential confounders. (C) 2016 Elsevier Ireland Ltd. All rights reserved.