The aim of this study was to analyze the point mutation of the exon 1 at codon 54 of the mannose (or mannan)-binding lectin (MBL) gene in healthy individuals of Chinese Hans and Mongolian population, and to find out any association between the plasma levels of MBL and the gene mutation frequency in both groups of individuals. Blood samples were collected randomly from 56 healthy individuals of Chinese Hans and 37 Mongolian. The detection of the point mutations of the MBL gene was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and detections for plasma levels of MBL were determined by using MBL ELISA kits. A MBL PCR method of assay was established with high specificity, and good reproducibility. By optimizing the PCR condition, the optimal annealing temperature was 55℃, and the lowest detection limit was 160 pg. No bands were found in non-specificity samples (HAV, HBV, HCV and TB), and the sequences of PCR products were the same as the expected ones. Also a MBL PCR-RFLP was established. Upon electrophoresis of the digested products in 3% agarose gel, there were 3 patterns: in which 2 bands correspond to molecule weight 232 bp and 93 bp; 1 band, corresponds to molecule weight 325 bp and 3 bands correspond to molecule weight 325 bp, 232 bp and 93 bp, respectively. Three bands of 325 bp, 232 bp and 93 bp of point mutations were found at codon 54 of MBL coding gene. Frequencies in healthy Han and Mongolian population were 0.2321 and 0.1757 respectively. The average plasma MBL concentration was 1998.750 μg/L, with SD of 1505.152 in 56 healthy Han population and 2525.676 μg/L, with SD of 1955.188 in 37 Mongolian. A negative correlation between MBL concentration and gene mutation frequency was found in healthy Han population. Frequency of point mutation was 1.00 when the MBL concentrations were below 100 μg/L; frequency of point mutation was 0.4524 when the concentration was 100 μg/L to 1000 μg/L; and the frequency of point mutation was 0.0156 when the concentration was over 1000 μg/L. Analysis of association between MBL concentration and gene frequency in healthy Mongolian population showed that frequency of point mutation was 1.00 when the MBL concentrations were below 100 μg/L and the frequency of point mutation was 0.4583 when the MBL concentrations were 100 μg/L to 1000 μg/L; no point mutation was found when the concentration was over 1000 μg/L. It is concluded that the frequencies of mutation at codon 54 of MBL coding gene had been determined in both healthy Hans and Mongolian population, and the frequency was higher in healthy Hans than that of Mongolian, but no statistical significance (χ 2=0.8574, P >0.05). The MBL level was lower in healthy Hans than in Mongolian population, but there was no statistical significance( t =1.448, 0.1< P <0.2). There was a negative correlation between frequency of point mutation and MBL concentrations in both Hans and Mongolian population( r =-0.62, r =-0.641). The aim of this study was to analyze the point mutation of the exon 1 at codon 54 of the mannose (or mannan) -binding lectin (MBL) gene in healthy individuals of Chinese Hans and Mongolian population, and to find out any association between the plasma levels of MBL and the gene mutation frequency in both groups of individuals. Blood samples were collected randomly from 56 healthy individuals of Chinese Hans and 37 Mongolian. The detection of the point mutations of the MBL gene was performed by polymerase chain reaction-restriction fragment length PCR (PCR-RFLP) and detections for plasma levels of MBL were determined by using MBL ELISA kits. A MBL PCR method of assay was established with high specificity, and good reproducibility. By optimizing the PCR condition, the optimal annealing temperature was 55 ℃, and the lowest detection limit was 160 pg. No bands were found in non-specificity samples (HAV, HBV, HCV and TB), and the sequences of PCR products were the same as the expec After electrophoresis of the digested products in 3% agarose gel, there were 3 patterns: in which 2 bands correspond to the molecule weight 232 bp and 93 bp; 1 band, corresponds to the molecule weight Three bands of 325 bp, 232 bp and 93 bp of the point mutations found in codon 54 of MBL coding gene. Frequencies in healthy Han and Mongolian population were 0.2321 and 0.1757 respectively. The average plasma MBL concentration was 1998.750 μg / L with SD of 1505.152 in 56 healthy Han population and 2525.676 μg / L, with SD of 1955.188 in 37 Mongolian. A negative correlation between MBL concentration and gene mutation frequency of point mutation was 1.00 when the MBL concentrations were below 100 μg / L; frequency of point mutation was 0.4524 when the concentration was 100 μg / L to 1000 μg / L; and the frequency of po int mutThe result was 0.0156 when the concentration was over 1000 μg / L. Analysis of association between MBL concentration and gene frequency in healthy Mongolian population showed that frequency of point mutation was 1.00 when the MBL concentrations were below 100 μg / L and the frequency of point mutation was 0.4583 when the MBL concentrations were 100 μg / L to 1000 μg / L; no point mutation was found when the concentration was over 1000 μg / L. It is concluded that the frequencies of mutation at codon 54 of MBL coding gene had been determined The MBL level was lower in healthy Hans than in Mongolian population, but There was no negative correlation between frequency of point mutation and MBL concentrations in both Hans and Mongolian population (r = -0.62, r = -0.641).