A surgical access assembly including a housing, an elongate access member and a zero closure valve including a valve periphery having a collar, a tapered segment extending inwardly from the collar and a second segment extending contiguously from the tapered segment. First and second lips depend from the second segment of the zero closure valve and define lip edges which are in approximated closed relation when the zero closure valve is in the closed position to define a slit. The first and second lips each include a proximal lip surface having an outer surface portion and an inner surface portion interconnected by a curved surface. A support rib depends from the proximal lip surface of each of the first and second lips to define a gap therebetween to be in spaced relation when the valve is in the closed position and being positioned to contact the surgical instrument during insertion through the first and second lips.