The present invention relates to a valve assembly for sealing a through passage of a catheter introducing device, comprising a sealing unit having a movable closing member connected to a biasing means, and a seat member arranged with a sealing surface around the aperture of the through passage, wherein the biasing means is arranged to urge the closing member to sealably abut against the sealing surface, corresponding to a closed position, so as to prevent flow of fluid through the valve. The invention also relates to a catheter introducer assembly comprising a valve assembly.
