The complete nucleotide sequence of hepatitis B virus (HBV) DNA from Dane particles of subtype adr was determined. The 3215-bp sequence showed the presence of genes for the surface antigen (226 amino acids) and core antigen (183 amino acids), in addition to two (long and small) open reading frames (ORFs) capable of coding the 843 and 154 amino acids. These ORFs differed from those of the other adr clones so far reported [Ono et al., Nucl. Acids Res. 11 (1983) 1747-1757; Fujiyama et al., Nucl. Acids Res. 11 (1983) 4601-4610]. The gene organization of HBV DNA was found to be well conserved irrespective of subtype. The direct repeat of the undecanucleotide sequence near the 5' ends of the short (S) and long (L) strands of HBV DNA and the two small direct repeats between both 5' ends were found to be characteristic structures.