the present invention provides a medical implant material comprising mammalian transglutaminase and a polymer , wherein the transglutaminase is provided in the absence of free divalent metal ions and wherein the polymer is associated with the transglutaminase binding protein . preferably , the transglutaminase is a tissue transglutaminase , which is coated on , impregnated into or covalently linked to the polymer . the polymer may be naturally occuring or synthetic , and may be biodegradable or non - biodegradable . the medical implant material may further comprise a reinforcing agent and / or one or more additional polymers . the invention further provides the use of a mammalian transglutaminase in a method for improving the biocompatibility of a medical implant material , the method comprising the steps of providing a medical implant material comprising a polymer associated with a binding protein for binding the transglutaminase , and treating said material with a mammalian transglutaminase .