The gene encoding protein p72, the major structural protein of African swine fever virus and one of the most immunogenic proteins in natural infection has been mapped and sequenced. The gene was mapped by using oligonucleotide probes deduced from amino acid sequences of tryptic peptides obtained from purified protein p72. This allowed the location of the gene in fragment EcoRI B of African swine fever virus DNA. The nucleotide sequence obtained from this region revealed an open reading frame encoding 646 amino acids corresponding to a protein with a calculated molecular weight of 73,096 Da. This open reading frame contains the coding information for all the sequenced tryptic peptides from protein p72. A search at the National Biomedical Research Foundation Data Bank did not reveal any significant homology with other described proteins.