To investigate the involvement of tumor-associated antigens such as sLe(a) and sLe(x), as well as Le(y) glycosphingolipid in the procoagulant activity of cancer cells, we examined the relationship between the inhibitory effect of anti-sLe(a) or anti-sLe(x) antibodies on the procoagulant activity of cancer cells, and cell surface expression of sLe(a) and sLe(x) antigens. We observed that the procoagulant activity of cancer cells which highly expressed sLe(a) or sLe(x) antigens (expression rate >70%) was significantly inhibited by the relevant antibodies. These data suggested that not only Le(y) but also sLe(a) and sLe(x) antigens play an important role in coagulation induced by various cancer cells.