Antibodies specific for carcinoembryonic antigen (CEA) induced polar redistribution of CEA which was expressed on the surface of human intestinal carcinoma cells grown in tissue culture. Polar redistribution occurred at 23 degrees C and 37 degrees C but not at 4 degrees C and was inhibited by sodium azide and cytochalasin B. Antibodies to isoantigen A did not react with CEA at the cell surface but did react with isoantigen A which was not redistributed by the antibody. Cells which expressed both CEA and isoantigen A were used to demonstrate that polar redistribution of CEA could be induced without altering the distribution of isoantigen A. The data indicate that CEA and isoantigen A can be expressed on the same cell as separate molecules.