Chlorella protothecoides accelerated the detoxification of chlordecone poisoned rats, decreasing the half-life of the toxin from 40 to 19 days. The ingested algae passed through the gastrointestinal tract unharmed , interrupted the enteric recirculation of the persistent insecticide, and subsequently eliminated the bound chlordecone with the feces. The detoxification was similar to that obtained with cholestyramine. Laboratory preparations were made to determine whether cell-free components retained the therapeutic properties of the whole cells. Acid and alkaline hydrolysis of the algae destroyed the cells except for the resistant cell wall components. One component was sporopollenin , a carotenoid polymer of limited natural occurrence among microorganisms and plants. Plant sporopollenin was not active, but algal cell walls and sporopollenin retained the therapeutic activity of the whole cells. The cells and cell walls have potential as detoxifying drugs for animals poisoned by chlordecone and other xenobiotic compounds with similar properties.