['Homozygotes for the normal (A) allele of mannose-binding lectin (MBL2) gene have higher risks to develop an early restenosis after eversion carotid endarterectomy (CEA). Activation of the lectin pathway is regulated by C1-inhibitor (C1-INH). The objective of the present study was to determine the predictive value of C1-INH in restenosis after CEA.', 'C1-INH and MBL-associated serine protease-2 (MASP-2) were determined in samples serially taken from 64 patients with CEA, who were followed-up with carotid duplex scan (CDS) examinations for 14 months. MBL2 genotypes were also determined. Patients with >50% restenosis had lower C1-INH levels at 6 weeks (P=0.0052) and at 4 days (P=0.0277) postsurgery. C1-INH levels at 6 weeks correlated inversely with the CDS values at 14 months (r=-0.3415, P=0.0058), but only in MBL2 A/A homozygotes (r=-0.5044, P=0.0015). Patients with low C1-INH levels (C1-INH <115%) had higher CDS values already at 7 months postsurgery. Patients with MBL2 A/A and low C1-INH levels at 6 weeks postsurgery had 13.97 (95% CI:1.95 to 100.21, P=0.0087) times higher risk to develop an early restenosis. Differences in the MASP-2 concentration were not associated with restenosis.'] Do low c1-inhibitor levels predict early restenosis after eversion carotid endarterectomy?