1. The initial rate of removal from the circulation of injected [(14)C] labelled chylomicron triglyceride is much slower in rats that have been injected with the non-ionic detergent, Triton WR 1339, than in normal animals. Pre-incubation of the lipid with Triton before its injection causes a further reduction in removal rate.2. After the injection of [(14)C]labelled chyle triglyceride into animals given Triton, the rate of disappearance of radioactivity falls markedly as the percentage of the labelled material remaining in the blood declines.3. A much smaller decrease in the rate of removal of injected chylomicron triglyceride occurs with increase in the size of the injected dose and with increase in the time interval between Triton and chylomicron triglyceride injections.4. Serum triglycerides labelled with (14)C are removed from the circulation of rats that have been given Triton at a much slower rate than [(14)C] labelled chylomicron triglycerides.