The effect of methylenebisphosphonic acid (MBPA) on glycosaminoglycan metabolism, adhesive and proliferative properties of human endothelial cells has been investigated. It was demonstrated that MBPA (100 microM) inhibited the synthesis of all studied groups of glycosaminoglycans, but promoted the accumulation of heparan sulphate in endothelial pericellular matrix. Simultaneously, the redistribution of hyaluronic acid from pericellular matrix to the conditioned medium was observed. The decreased adhesion of endothelial cells to immobilized hyaluronic acid was not mediated by the alterations of CD44 expression. It was also demonstrated that MBPA affected the proliferative properties of endothelial cells. The alterations of glycosaminoglycan metabolism are considered to be involved in antiangiogenic effects of MBPA.