Recently, schistosomiasis is considered mainly as an immunological disease and it is essentially a cell-mediated immunity with a certain state of immunosuppression. In patients with schistosomal colorectal masses IgG and IgM showed significant elevation to undergo marked reduction after surgical resection of the mass or the polypi. Several mechanisms had been put to explain the preoperative raise of both IgG and IgM serum levels. After surgical treatment there was a significant decrease in migration inhibition index denoting increased sensitivity of T-lymphocytes to the soluble egg antigen [SEA] , i. e. the cell-mediated immunity had regained some of its functions as measured by this parameter