Chickens fed a high-protein, high-cholesterol diet develop, in addition to hypercholesterolhemia and hyperlipaemia, a high level of plasma metachromasia. This is related to the cholesterol content of the plasma and not to age or period of cholesterol feeding. After the removal of chylomicra the plasma has a greatly lengthened recalcification time pointing to the presence of a heparin-like substance.THE effects of cholesterol feeding on the blood chemistry of the chicken on which pioneer studies were made by Kawamara [1927] and Kesten et al. [1936] have been reviewed by Pick et al. [1959]. During experiments on the effect of pancreatic enzymes on lipaemia [Hall, 1964]