A protective cap (1) for application on a medical device such as a medical vial (2) comprising a membrane holder (3) in which a resilient membrane (18) is mounted. The protective cap (1) is provided with connection means (10) for connecting the cap (1) to the medical device (2). The resilient membrane (18) comprises a piercing portion (20) and a sealing portion (22) and is mechanically and/or adhesively held in the protective cap (1) and is arranged to be brought into sealing contact with a receiving portion of the medical device (2) when the protective cap (1) is applied on the medical device (2).
