Mannose-binding lectin (MBL) can bind with a wide range of pathogens and can activate through lectin pathway or enhances opsonophagocytosis. MBL is encoded by the MBL2 gene and single-nucleotide polymorphisms (SNPs) in the promoter and exon have functional effects on serum levels of MBL. MBL deficiency has been shown to predispose to infectious diseases. We assess whether or not, the variant MBL alleles are associated with susceptibility to dengue infection. Patients with confirmed dengue infection who were admitted to King Chulalongkorn Memorial Hospital during a calendar year were studied. Controls were patients without dengue infection. Deoxyribonucleic acid (DNA) was extracted from 50 μl of peripheral blood mononuclear cell (PBMC) using the DNA Blood Mini Kit. The SNPs in the promoter (-221 X/Y) and exon 1 (codon 54 A/B) of MBL2 gene were genotyped by using 2 separate cycling reactions of the TaqMan allele discrimination system. Serum levels of MBL were determined by double-antibody sandwich ELISA. Chi-square was used for statistical analysis. Serum MBL levels and genotypes were determined in 110 dengue patients (mean age 18.1 years; 62 males and 48 females) and 42 controls (mean age 25.8 years; males: females = 1:1). Our study showed that YB haplotype is associated with low serum levels of MBL. There was no association between MBL2 gene polymorphisms and susceptibility to dengue infection. The higher frequency of YB in dengue patients than in controls suggesting the likelihood of an association. Further studies are warranted.