A dispenser for liquid soap includes a compressible nipple having an annular flange mountable on a soap container in communication with the outlet opening thereof, and clamping therebetween a valve assembly including a slitted flexible diaphragm and a backing disc. The disc has a discharge opening in alignment with a check valve slit in the diaphragm for controlling discharge of soap into the nipple for dispensing upon compression of the nipple. The disc and the nipple flange respectively have annular grooves formed in the facing surfaces thereof, a vent valve slit in the diaphragm being aligned with these grooves. The flange groove communicates with the outside of the nipple through a vent opening and the disc groove communicates with the outlet opening of a container through a vent orifice in the disc. The diaphragm thickness is less than the depth of the disc groove and greater than the depth of the nipple flange groove, so that it can open only inwardly to permit air to enter the container, but cannot open outwardly to permit discharge of soap through the vent opening.