Alpha-nl interferon (Wellferon), alpha-2a interferon (Roferon), and alpha 2b interferon (Intron-A) inhibited accumulation of intracellular replicative forms of hepatitis B virus (HBV) in chronic producer cells by inhibiting accumulation of RNase-resistant HBV RNA. In contrast, the nucleoside analog PTC (cis-5-fluoro-1-[2-(hydroxymethyl)-1,3-oxathiolan-5-yl]cytosine) inhibited the accumulation of HBV DNA.