The complete Dane particle consists of two serologically and morphologically different components: Core (HBc) and Surface (HBs). HBc is located almost exclusively in the liver cell nucleus and can be demonstrated by immunofluorescence and electron microscopy, but not by light microscopy. HBs is located exclusively in the cytoplasm and can be demonstrated by immunofluorescence (IF) and, if present in excess, by electron an light microscopy (as ground-glass hepatocytes). The combined analysis with IF, electron and light microscopy of biopsy specimens taken from patients with different forms of hepatitis with and without immunosuppresive therapy allows recognition of at least four different reaction patterns: 1. Immunosuppression type (= HBc-predominance type), 2. Elimination type, 3. Aggressive type (= HBc+s equivalence type, 4. Carrier type (= HBs-predominance type). The patterns of HB-Antigen components are of prognostic value as to the clinical course of hepatitis. These findings strongly suggest that immune responsiveness determins the reaction pattern, the key mechanism being immune elimination of affected cells. In addition, these findings stress the role of the immune system in regard to the variability to the clinical course of hepatitis B, and shed light on morphological correlations.