Antisera against the zinc glycinate marker (ZGM) were produced in New Zealand White rabbits with induced tolerance to normal tissue components and CEA, and in mature, previously uninoculated rabbits for use in immunofluorescent histologic localization of ZGM in colon cancers and other tissues. Analysis of the antisera by immunodiffusion and counterimmunoelectrophoretic techniques showed them to be specific for ZGM when tested with ZGM, carcinoembryonic antigen, normal tissue extracts, or cell elements of normal blood.