Purified avian myeloblastosis virus (AMV) polymerase consisting of alpha,beta subunits has been shown to act processively in catalyzing DNA synthesis primed with 34S AMV RNA oligo(dT), poly(A)-poly(dT), and poly(I)-poly(dC). DNA transcripts prepared with 34S AMV RNA-oligo(dT)14 and AMV polymerase (alphabeta) have been shown to have a molecular weight of 1.05 X 10(6), or approximately one-third the size of the 34S RNA genome. Polymerase subunit alpha acts nonprocessively with the above templates.