Intestinal hypersensitivity reactions during parasitic helminth infections are T-cell-dependent. Little is known about the characteristics of T-cells that initiate and regulate intestinal inflammation or about how they do this. In this paper data are presented that indicate that during Trichinella spiralis infections in mice T-cells regulate intestinal inflammation in the same way that they regulate delayed-type hypersensitivity reactions in the skin and cellular immune responses against tumors.