The Hanganutziu-Deicher (HD) antigen is a heterophilic antigen with N-glycolylneuraminic acid as the terminal carbohydrate, and has attracted much attention as one of tumor-associated antigens. This antigen is absent from normal tissues of human and chicken but expressed in human neoplasms. Extensive research on HD antigen has not be made yet to show the intimate correlation with human neoplasm, but it is attracting an attention as a diagnostic marker for the definition of cancer. We made two different chicken monoclonal antibodies against HD antigen as a pathological tool for hepatocellular carcinoma (HCC). The hybrid cell, which produced antibodies, were prepared by means of fusion technology with HD3 antigen-immunized chicken spleen cells and HAT-sensitive chicken B cell line termed R27H4. The two antibodies had a different characteristic, one recognized only glycolipid, and the other recognized glycoprotein as well as glycolipid. Glycolipid type HD antigen and glycoprotein type HD antigen were identified by using two chicken anti-HD monoclonal antibodies. Glycolipid type HD antigen was detected by flow cytometry in 4 out of 24 HCC samples (87.5%). In our study, increased serum levels of IgG type and/or IgM type HD antibodies were observed in 21 out of 24 patients with HCC (87.5%). The presence of these antibodies is attributable to the expression of the HD antigen in cells of HCC. Eleven out of 24 patients with HCC were negative for AFP and PIVKA-II, and 10 out of these 11 patients (90.9%) were positive for anti-HD antibodies. We consider that patients with HCC should be screened for HD antigen and antibody for an early diagnosis of hepatocellular carcinoma; the same as for AFP and PIVKA-II both of which are tumor-associated antigens that have been associated with for hepatocellular carcinoma.