A tissue adhesive for contacting a tissue site, the tissue adhesive comprising: a mixture of natural polymers; and an activating agent enhancing the adhesive properties of the mixture of natural polymers. And a tissue adhesive for contacting a tissue site, the tissue adhesive comprising: a mixture of natural polymers; and an aqueous solution of a water soluble starch or a water soluble starch derivative which forms a gel with the addition of the mixture of natural polymers.