Abstract: The present invention provides a method for medical treatment comprising introducing into a human or animal a medical device selected from the group consisting of stents, catheters, cannulas, plugs and constrictors where the medical device comprises ionically crosslinked polymer. The invention further provides a method for medical treatment of humans and animals comprising introducing into them an ionically crosslinkable polymer and a crosslinking ion followed by crosslinking of the polymer to form a medical device selected from the group consisting of stents, catheters, cannulas, plugs and constrictors.