A 520-base pair human IFN-alpha gene was isolated by PCR method twice from chromosome DNA of a Chinese (Han Nationality) fetal liver. The nucleotide sequences were determined. These two separately amplified DNA fragments shared the completely identical nucleotide sequence but possessed C and G at positions 410 and 541, respectively, which differ from those of IFN-alpha 1 and IFN-alpha D previously described. Therefore the deduced amino acid sequence would have an Ala at position 114 and a Val at position 158. At all other sites it has the same amino acids as those in IFN-alpha 1 and IFN-alpha D. We recommend that IFN-alpha D gene, IFN-alpha I gene and IFN-alpha I/158V gene found in our laboratory, be named IFN-alpha 1a gene, IFN-alpha 1b gene and IFN-alpha 1c gene.