Abstract: A self-sealing catheter valve that includes a flexible tubular part having a distal opening and an opposite proximal opening, and a proximal valve part. The proximal valve part has a curved self-sealing flexible diaphragm disposed inside the flexible tubular part and has a base perimeter united with a circumferential wall of the flexible tubular part. The curved self-sealing flexible diaphragm has a concave surface facing towards the proximal opening, and a convex surface facing towards the distal opening, and a flexible diaphragm wall of the curved self-sealing flexible diaphragm has a traverse slit. The self-sealing catheter valve provides an efficient self-closing mechanism for a peripheral catheter assembly and constitutes an efficient barrier against potential contagious spread from the patient to the surrounding environment by blood born disease e.g. HIV, hepatitis and Ebola viruses.