Systemic arterial stiffness is increased in patients after Kawasaki disease (KD). Recently, associations between mannose-binding lectin (MBL) gene mutation and coronary complications in infants with KD and atherosclerosis in adults have been reported. We tested the hypothesis that MBL genotype modulates arterial stiffness in children after KD. Seventy-one KD patients (42 with and 29 without coronary aneurysms), aged 9.5 +/- 3.7 y, and 41 age-matched controls were studied. We determined and compared their blood pressure, brachioradial arterial stiffness as determined by pulse wave velocity (PWV), fasting total cholesterol, serum MBL level, and MBL genotype. Additionally, the modulating effects of different MBL expression genotypes [high level (HL) versus intermediate or low level (IL/LL)] on arterial stiffness in different groups were assessed. The MBL genotype distributions did not differ between patients and controls (p = 0.41) or between patients with and without coronary aneurysms (p = 0.42). Patients with IL/LL expression genotypes had significantly faster PWV than those with HL expression genotypes (7.93 +/- 1.38 m/s versus 6.67 +/- 2.28 m/s, p = 0.027). This genotype-modulating effect is more pronounced in patients without (HL 8.86 +/- 0.77 m/s versus IL/LL 6.48 +/- 2.32 m/s, p = 0.02) than those with (HL 7.50 +/- 1.41 m/s versus IL/LL 6.80 +/- 2.28 m/s, p = 0.32) coronary aneurysms. Multiple linear regression analysis identified age (beta = 0.26, p = 0.012), being a Kawasaki patient (beta = 0.22, p = 0.015), and MBL IL/LL genotype subgroup (beta = 0.20, p = 0.03) as significant determinants of arterial stiffness in the entire cohort. In conclusion, MBL genotype modulates arterial stiffness, an important cardiovascular risk factor, in children after KD.