Mussel Adhesive Protein (MAP) was applied to either denuded rabbit cornea, or dialysis membrane with a 50,000 dalton molecular weight cut-off. The permeability of corneal endothelium or bare stroma was compared with demambranized stroma coated on one surface with MAP. The permeability of dialysis membrane, both in the presence and absence of MAP, was also determined to inulin (5,000 daltons) and dextran (40,000 daltons). Corneal endothelial permeability was much less than that of bare stroma, and coating denuded stroma with MAP on one surface had no effect on stromal permeability. Dialysis membrane permeability was not reduced after coating with different thickness of MAP, indicating that MAP offers little resistance to the passage of even large non-electrolytes and can serve as a basement membrane for cellular or tissue attachment without impairment of nutritional supply to the overlying cells.