Recent animal studies show that endothelial cells in liver sinusoids are the main site for removal of sodium hyaluronate from the circulation. Few data with respect to hyaluronate metabolism are available in man. Serum hyaluronate levels were measured in 119 patients with liver disease by a sensitive assay. The hyaluronate level was significantly increased in liver cirrhosis, in comparison with healthy controls and with patients with noncirrhotic liver disease. The results suggest a role for the human liver in elimination of hyaluronate from circulation. Quantification of serum hyaluronate may be a useful test of liver endothelial cell function.