Substances that elute from denture base resins may inhibit cell growth and disrupt various metabolic processes. This study investigated the effects on cell lipid metabolism of eluates from several denture base resins. Cultured oral epithelial cells were exposed in vitro to eluates of discs made from several denture base resins. Lipid metabolism of the cells was measured using isotopic labeling with 14C-acetate. Results demonstrated that the metabolism of several lipid classes found mainly in the cell membrane was altered by the resin eluates. Eluate from one resin caused the appearance of two previously unrecognized classes of lipids. The alterations of the cell lipids and the presence of the previously unrecognized lipids may be the basis for some clinically evident cytotoxic and allergic reactions.