The entire genome of human hepatitis B virus (HBV) occurring in Latvia was sequenced. This sequence, which is 3182 nucleotides long, was compared with the other previously published HBV genomes and was shown to share maximum homology with HBV subtype ayw DNA. The coordinates of 4 main open reading frames as well as hairpin structures are very well conserved in the two genomes. The distribution of nucleotide substitutions among different HBV genomes suggest that the open reading frames P and X can fulfil a coding function. On the basis of primary structure comparison for hepadnaviral DNAs several evolutionary conclusions can be drawn.