The present disclosure is directed to a flexible cap for a medical fitting, such as a luer-lock fitting. The flexible cap includes a cap component defining a top surface, a cylindrical wall extending opposite from the top surface of the cap component, and an inner sealing surface. The cylindrical wall defines a hollow interior configured to receive an internal tapered sealing wall of a male connector of the medical fitting so as to form a seal with an outer surface of the tapered sealing wall. Further, the inner sealing surface of the flexible cap is configured within the hollow interior. Thus, when the tapered sealing wall of the male connector of the medical fitting is received within the hollow interior of the cylindrical wall, the inner sealing surface of the flexible cap seals the fluid passageway of the tapered sealing wall.