Abstract: A durable water- and oil-resistant, breathable thin microporous membrane (90) exhibits good hand, feel, and drape. The structure of microporous membrane is a thin polymer matrix that includes a polyolefin material having a bulk region (186) between first and second major surfaces (184, 194). The bulk region includes multiple interconnecting micropores (87) extending between the surfaces to form a polyolefin membrane (170) that exhibits inherent hydrophobicity and moisture vapor transmission properties. An applied fluorochemical treatment (92) imparts oleophobicity to the polyolefin membrane by imparting a lower surface energy to polyolefin membrane to provide oil and surfactant resistance, and to maintain moisture vapor transmission through the microporous structure. Preferred embodiments of microporous membrane also include an inorganic filler material such as calcium carbonate.