112 cases, of varying ages, which were diagnosed as having carcinoma of the bladder by cystoscopy and biopsy from the tumor, were investigated for the presence of alphafetoprotein (AFP) in the sera. 59 (52.6 %) out of the total, showed positive results, and no false positive results occured. Radioimmunoassay was capable of increasing the positivity rate still further. All of the cases were prov...