AbstractBarrier membranes for guided tissue regeneration (GTR) to treat bone defects have to satisfy criteria of biocompatibility, cell‐occlusiveness, spacemaking, tissue integration, and clinical manageability. In this study, the morphological and mechanical properties of two commercial biodegradable membranes (Resolut® LT and Biofix®) as a function of the incubation time have been compared. Moreover, their permeability to both fluids and epithelial cells as well as the bacteria adhesion have been evaluated. The membranes are asymmetric and composed of a dense polymeric layer coupled with nonwoven (Resolut® LT) or woven (Biofix®) fibers. Both of the membranes, when incubated in complete culture medium, completely lose the structural and mechanical properties within 30 days. Moreover the results of solute permeability show that Resolut® LT and Biofix® membranes cannot be considered selective membranes to the solute crossing. On the contrary, they act as a barrier to the passage of the gingivial cells and to S. mutans bacteria. © 2001 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 58: 427–435, 2001