The cytotoxic potential of autopolymerized pour and dough type resins and heat cured resins was studied by in vitro cell culture techniques. Human epithelial cells (NCTC 2544) were grown in Eagle's minimal essential medium on the surface of the polymer disks. The cell multiplication on the surface of the specimens was measured. One heat cured resin and one pour type resin demonstrated a slight cytotoxic effect. The other polymers gave a moderate cytotoxic effect. The study did not indicate any difference in the cytotoxicity of the polymers when manufactured by alternate processing methods.