The complete nucleotide sequence of the genome of the fish rhabdovirus infectious haematopoietic necrosis virus (IHNV) has been determined after cDNA cloning of the viral genomic RNA. Sequence analysis showed the presence of six open reading frames encoding the nucleoprotein N, the matrix proteins M1 and M2, the glycoprotein G, a so-called non-structural protein NV, and the RNA polymerase L. The genome organization is 3'N-M1-M2-G-NV-L 5'. The extreme 5' and 3' ends of the genome were sequenced after RNA ligation or RACE. Prokaryotic expression products of the open reading frames predicted to encode the matrix proteins M1 and M2, the glycoprotein G and the NV protein reacted with rabbit anti-IHNV serum thereby confirming their identity. This is the first complete nucleotide sequence of a fish rhabdovirus. Knowledge of the complete sequence is an essential prerequisite for future manipulation of the genome and also serves to provide gene- and protein specific reagents for use in further examination of the replication of the fish rhabdoviruses.