A surgical cast venting material comprises a waterproof, flexible substrate made of a plastics material and having first and second sides. The first side has a plurality of shallow, concave recesses distributed over the substrate and spaced-apart from one another while the second side has a plurality of protrusions distributed across the substrate. The substrate is perforated with a plurality of small holes distributed across its length and width. Also, a surgical cast venting device is disclosed for venting a bent region of a patient's limb. It has a flexible, central portion that can cover a major part of the bent region of the limb including opposite side surfaces and a front or rear surface. The device also has flexible connecting straps extending from two corners of the central portion.