The PIK3CA gene, oncogenic gene located on human chromosome 3q26.3, is an important regulator of cell proliferation, death, motility and invasion. To evaluate the role of PIK3CA gene in the risk of Korean lung cancer, genotypes of the PIK3CA polymorphisms (rs11709323, rs2699895, rs3729679, rs17849074 and rs1356413) were determined in 423 lung cancer patients and 443 normal controls. Statistical analyses revealed that the genotypes and haplotypes in the PIK3CA gene were not significantly associated with the risk of lung cancer in the Korean population, suggesting that these PIK3CA polymorphisms do not contribute to the genetic susceptibility to lung cancer in the Korean population.