I evaluated a commercially available polyacrylamide column (Clinetics Corp.) for use in assaying for carcinoembryonic antigen. The procedure eliminates the need for dialysis and 50 samples, assayed in duplicate, may be completed in 5 h. In general, results by this technique are 1.0 microgram/L (range 0.5-2.0) lower than by the conventional dialysis method (r = 0.9876). Sensitivity approximates 0.5 microgram/L. Within-day precision for two pools of patients' plasma (n = 10) was mean = 2.29 (SEM 0.05) microgram/L with CV = 6.55% and mean = 10.61 (SEM 0.10) microgram/L with CV = 2.92%, respectively; between-day precision (n = 6) was mean = 3.90 (SEM 0.16) microgram/L with CV = 10.0% and mean = 10.1 (SEM 0.37) microgram/L, CV = 8.91%, respectively. The precentage analytical recovery of added carcinoembryonic antigen was about 80% at concentrations of approximately 8 and 12 microgram/L, 73% at 18 microgram/L.