ABSTRACT—A new ultrastructural cytoplasmic marker designated as type 2, and distinct from type 1 previously associated with NA‐NB hepatitis in chimpanzees, was found in hepatocytes of two patients and of one experimentally infected chimpanzee. These cases represent a minority of all cases we studied as presumed NA‐NB viral hepatitis. Type 2 marker consists of tubular structures composed of an assembly of ring‐like units coated with smaller uniform fragments, accumulated in different patterns in dilated cisternae of the endoplasmic reticulum. Preliminary data using immunofluorescence with NA‐NB hepatitis convalescent serum and antiserum against fibrinogen are reported. Type 2 marker may represent a different agent or a different reaction pattern to one agent of NA‐NB viral hepatitis. Its features are compared with those of