Serum seromucoid estimation was carried out in 60 normal controls and 100 patients. (1) The serum seromucoid values in normal subjects ranged between 37-5-127 mg.% (69-35 +/- 17-84). (2) Serum seromucoid levels were found to be increased in patients of abdominal tuberculosis (210-95 +/- 86-49). These values corresponded directly to the severity of the disease. (3) Seromucoid levels came down to normal after three months of antitubercular treatment. (4) There was an inverse relationship between serum albumin and seromucoids. (5) Serum seromucoids were also found to be increased in patients of amoebiasis (157-54 +/- 37-61), with associated active colonic or hepatic disease. Asymptomatic cyst passers had normal levels of serum seromucoids. (6) Serum seromucoid values were within normal limits in patients with tropical sprue and irritable colon syndrome.