We demonstrate electroadhesion (EA), i.e., adhesion induced by an electric field, between cationic hydrogels and animal tissues. When gel and tissue are placed under an electric field (DC, 10 V) for 20 s, the pair strongly adhere, and the adhesion persists indefinitely thereafter. Applying the field with reversed polarity reverses the adhesion. EA is especially strong in the case of the aorta, cornea, lung, and cartilage. We then show the use of EA to seal cuts or tears in tissues or model anionic gels. Electroadhered gel-patches provide a robust seal over openings in bovine aorta. Moreover, a gel sleeve is able to rejoin pieces of a severed tube (an anastomosis). These studies raise the possibility of using EA in surgery while obviating the need for sutures or staples. Advantages include the ability to achieve adhesion on-command, and moreover the ability to reverse this adhesion in case of error.