The substances tested were heparin-Na, Na alginate, chondroitin-Na, dextransulfate-Na, Liquoide, and natural heparinoids. After determination of a dose-response curve for metachomasia with heparin as a standard, it was possible to determine heparinoids as heparin equivalents The ratios between metachromasia and uronic acid content, metachromasia and clearing activity, and between uronic acid and clearing effect have been studied.