The invention relates to a closing cap for containers, especially bottle-shaped containers, which are filled with medical liquids, especially with liquids for infusion or transfusion. Said closing cap comprises a removal and injection site (6, 7) having a first opening (8) for removing the liquid and being obturated by a first pierceable self-sealing membrane (10), and a second opening (9) for injecting an additive and being obturated by a second pierceable self-sealing membrane (11), the first and second membrane being configured differently. Since the port system has differently configured membranes, the removal and injection site can be optimally adapted to the specific requirements during removal of a liquid and injection of an additive. According to preferred embodiments of the invention, the membranes are clamped by means of a snap-fit retaining plate fastened inside the cap.
