The right variable region of the genome of a pathogenic strain of African swine fever virus (ASFV), Malawi LIL20/1, has been sequenced and 15 open reading frames (ORFs) identified by computer analysis. Eight of these ORFs were found to be similar to previously described ASFV ORFs and three of these belong to two previously described multiple gene families (MGF), 360 and 110. Four of the remaining five ORFs belong to a novel MGF, designated MGF 100, and the last ORF encodes a protein that is similar to the virus structural protein, p22. Copies of MGF 110 and the gene coding for p22 have previously been characterized only at the left end of the ASFV genome. The organization of these genes suggests evolution by duplications, deletions and sequence transposition from one end of the genome to the other. Sequence comparisons of members of MGF 360 suggest that the Malawi LIL20/1 genome has undergone separate DNA rearrangements compared to the Ba71V genome. Lastly, one ORF was found to be similar to the myeloid differentiation primary response protein, MyDll6 and to the herpes simplex virus neurovirulence-associated factor ICP34"5.