Uniaxially oriented microporous breathable films having exceptional toughness transverse to the direction of orientation are disclosed herein. Such films include a particulate filler and a nonelastic material including a copolymer of ethylene with at least one C.sub.4 -C.sub.8 .alpha.-olefin monomer, such copolymers being described in the trade as "super tough", "next generation", etc., and being prepared with "new" or "improved" catalyst systems or with metallocene or similar single-site catalysts. A method of manufacture is also disclosed.