A bandage bag provides the dual functions of holding a medical apparatus to a patient for daily wear and of serving as a waterproof bandage, especially for a catheter and its insertion site. The bandage bag comprises a bag and two adhesive layers. The bag opens along a first edge. One adhesive layer is placed along the other three edges on the anterior side of the bag. The second adhesive layer is placed along the first edge on the posterior side of the bag. The bag is attached to a patient's arm near the insertion site using the second adhesive layer. The catheter tubing and port is placed in the bag. The bag is then folded over so the first adhesive layer on the anterior side faces the arm and covers the insertion site, forming a waterproof bandage for the insertion site and the medical apparatus.