The present invention provides adhesion barrier compositions based on a solution of at least one of a biodegradable polyester amide (PEA), polyester urethane (PEUR), or polyester urea (PEU) polymers, dissolved in a biocompatible solvent. The compositions can be applied to a tissue surface, such as in open surgery, as a viscous liquid which forms an adhesive film upon being sprayed or painted onto the tissue surface. Alternatively, the composition can be applied to the tissue surface as a preformed solid layer or double layer (either porous or non-porous) that adheres to the tissue surface. In open surgery, the invention adhesion barrier compositions are used to separate opposing tissue surfaces or tissue-organ surfaces while injured tissues heal, for example in the abdomen or pelvis
