An adhesive including a mixture of isocyanate capped molecules formed by reacting multi-isocyanate functional molecules with multi-functional precursor molecules including terminal functional groups selected from the group consisting of a hydroxyl group, a primary amino group and a secondary amino group. Preferably, the functional groups are hydroxyl groups. The multi-functional precursor compounds are biocompatible. Multi-amine functional precursors of the multi-isocyanate functional molecules are also biocompatible. As discussed, above, the mixture of molecules preferably has an average isocyanate functionality of at least 2.1 and, more preferably, has an average isocyanate functionality of at least 2.5. As also described above, the mixture of molecules preferably has a viscosity in the range of approximately 1 to approximately 100 centipoise. The mixture of molecules forms a crosslinked polymer network upon contact with the organic tissue in the presence of water. The crosslinked polymer network is biocompatible and biodegradable. The crosslinked polymer network degrades into degradation products including the precursor molecules and the multi-amine functional precursors.