Mannose-binding lectin (MBL) is able to bind pathogens as an opsonin and plays an important role in the innate immunity. The aim of the present study was to determine the frequencies of the MBL gene variants in the Turkish population and to examine the presence of any association between MBL variants and development of tuberculosis (TB) in adults and recurrent respiratory tract infections in children. Two structural gene mutations in exon 1 of MBL gene (codon 54 and codon 57) were studied. The overall distribution of genotypes did not significantly differ between controls and TB patients/children with recurrent respiratory system infections. The frequency of allele B was calculated as 0.14, 0.09 and 0.06 for control, TB patients and children with recurrent respiratory system infections, respectively. It was found to be significantly lower in children with recurrent respiratory system infections than in controls (chi2: 4.68, d.f: 1, p: 0.030).