A patient with constrictive pericarditis, secondary intestinal lymphangiectasia, and protein-losing enteropathy was demonstrated to have the characteristic immunologic deficiency associated with intestinal lymphangiectasia: hypogammaglobulinemia, lymphocytopenia, cutaneous anergy, impaired allograft rejection. and diminished in vitro lymphocyte proliferative responses. Following surgical correction of the cardiac abnormality, the intestinal lymphangiectasia and protein-losing gastroenteropathy resolved and was accompanied by a slow but progressive return of normal immune function. This documented reversal of the immunologic deficiency in intestinal lymphangiectasia supports the concept that the immune defect in this syndrome is due to the excessive loss of lymphocytes and immunoglobulins into the gastrointestinal tract.