Plasma exchange was performed in patients with recurrent colon cancer with evaluable liver metastasis or abdominal tumor with dissemination. This therapy was undertaken a total of 19 times in 11 cases. The cases were divided into effective and ineffective cases according in terms of the clinical effects, and changes in blood parameters and prognosis were examined in each case. Subjective symptoms, such as increase in appetite and disappearance of general fatigue or pain, were remarkably improved in 6 cases, and these patients were allowed to be discharged from the hospital. Marked regression of hepatomegalia was observed in 2 cases out of these 6 cases, but no remarkable effect was noted in patients with abdominal dissemination. In the effective cases the following parameters were significantly improved; beta- and gamma-globulin of serum protein fractions, IgG, IgA and IgM of immunoglobulin, alpha 2-macroglobulin, ceruloplasmin, and transferrin. However, since these effects are temporal and short-lived, one must consider applying plasma exchange therapy in conjunction with anticancer drugs, and the like. Plasma exchange seems applicable to cases of colon cancer with metastasis in the liver, because this therapy showed improvement in clinical symptoms, decreased hepatomegaly and prolonged survival.