A needleless syringe connector cap to be provided to a container having an aperture at its top, said cap comprising an elastically deformable plastic valve body to be provided in or above said aperture at the top of the container, said valve body having a top surface and a bottom surface, wherein said valve body comprises a first passage and a second passage, each passage extending through the valve body from the top surface to the bottom surface thereof, wherein said first passage comprises a first cross-slit valve in the extreme lower end of said passage, wherein said first cross-slit valve is embodied as an aeration valve, and wherein said second passage comprises a second cross-slit valve in the extreme lower end of said passage, wherein said second cross-slit valve is embodied as an aeration valve, wherein the first passage is adapted to receive a first tapered syringe tip and the second passage is adapted to receive a second tapered syringe tip, wherein when fluid is withdrawn from a container to which the cap is provided through the first (second) passage using a first (second) tapered syringe tip to which said first (second) passage is adapted, the second (first) cross-slit valve opens in response to an underpressure in said container resulting from said withdrawal, so as to aerate said container.
