The invention is directed to a composite nonwoven fabric comprising first and second nonwoven webs of spunbonded substantially continuous thermoplastic filaments, and a nonwoven hydrophobic microporous web of thermoplastic meltblown microfibers sandwiched between the first and second nonwoven webs. The filaments of the nonwoven spunbond webs are formed of continuous multiconstituent filaments which include a lower melting gamma radiation stable polyethylene polymer component and one or more higher melting gamma radiation stable polymer constituents, wherein a substantial portion of the surfaces of the multiconstituent filaments consists of the lower melting gamma radiation stable polyethylene constituent. The nonwoven hydrophobic microporous web is formed from a gamma radiation stable polyethylene polymer. The webs are bonded together to form the composite nonwoven fabric by discrete point bonds in which the polyethylene constituent of said multiconstituent filaments and the polyethylene of said third nonwoven web are fused together.