The growth inhibitory effects of D-glucosamine hydrochloride (GlcNH2·HCl), D-glucosamine (GlcNH2) and N-acetyl glucosamine (NAG) on human hepatoma SMMC-7721 cells in vitro were investigated. The results showed that GlcNH2·HCl and GlcNH2 resulted in a concentration-dependent reduction in hepatoma cell growth as measured by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. This effect was accompanied by a marked increase in the proportion of S cells as analyzed by flow cytometry. In addition, human hepatoma SMMC-7721 cells treated with GlcNH2·HCl resulted in the induction of apoptosis as assayed qualitatively by agarose gel electrophoresis. NAG could not inhibit the proliferation of SMMC-7721 cells. GlcNH2·HCl exhibited antitumor activity against Sarcoma 180 in Kunming mice at dosage of 125˜500 mg/kg, dose of 250 mg/kg being the best. GlcNH2·HCl at dose of 250 mg/kg could enhance significantly the thymus index, and spleen index and could promote T lymphocyte proliferation induced by ConA. The antitumor effect of GlcNH2·HCl is probably host-mediated and cytocidal.