We analysed the C3*S and C3*F polymorphism of the third component of the complement (C3), first at the protein level by the electrophoresis of the plasma on agarose gel and second on the gene level by the ARMS PCR technique. We determined the phenotypic and genotypic frequencies of the C3 on a sample of 90 patients suffering from the obstructive chronic bronchopneumopathy (OCBP) disease. Comparisons have been done with frequencies observed on a control sample of 437 healthy individuals from the Tunisian population in order to establish a putative correlation between the polymorphism studied and the disease. Frequencies of the C3*S and C3*F alleles in OCBP patients are 0,788 and 0,212 respectively. They are not significantly different from those observed in control sample (0,834 and 0,152 respectively). Therefore, no correlation is observed between the C3 polymorphism and the risk of developing the OCBP disease.