The van den Bergh reaction1for bile pigment in the blood was introduced in 1918. As originally proposed, the determinations were made with the blood serum. During the twelve years that have elapsed, the test has received general and widespread acceptance. Today, both in the original technic and in the modifications, most important of which is the Thannhauser and Andersen method,2serum is still employed. McNee and Keefer3were the first to suggest the use of plasma instead of serum. These workers applied the original van den Bergh technic to the plasma obtained from oxalated blood in the proportion of 0.2 cc. of 10 per cent potassium oxalate to from 10 to 15 cc. of whole blood. The results led them to assert that plasma and serum may be utilized equally well. Shay and Schloss4disagreed with these observers. In a series of eleven simultaneous examinations of serum and plasma