Sixteen cirrhotic patients with ascites and HBs antigen (HBsAg), were chosen for this study. Serum and ascitic fluid samples were tested for Ag, total proteins, electrophoretic pattern and immunoglobulin IgG, IgA, IgM and IgE. Transmission of HBsAg through the peritoneal membrane was confirmed. All protein fractions and immunoglobulins were presented in the ascitic fluid. Seven patients with ascites due to intra-abdominal neoplasms were also studied as controls. Significant differences were observed and are discussed.