A medical access device is adapted to receive an instrument and comprises a housing defining an inner channel and a valve disposed in the channel to form a seal with the housing. The valve includes an outer wall and a pair of inner walls extending in distally converging relationship to define a slot. At least one compression member extends between the outer wall and an associated one of the inner walls. The compression member is compressed in response to insertion of the instrument and exerts a force on the associated inner wall when compressed to reduce leakage of the valve when the instrument is inserted. A funnel is provided at the distal end of the valve to facilitate backloading of the instrument.