Abstract: A medical cast protective structure apparatus and methods are used to protect against unsanitary contamination of a medical cast. A medical cast has a hardened exterior layer and a plush interior layer. A water-resistant fabric cover has a substantially cylindrical shape and is positioned over at least a portion of an exterior of the medical cast and a terminating end of the medical cast. An annular pocket is formed in a first end of the fabric cover, wherein the first end of the fabric cover is positioned abutting the plush interior layer of the medical cast. A biasable clip is positioned within the annular pocket, wherein the biasable clip is movable between collapsed and expanded states, wherein in the expanded state, the annular pocket with biasable clip therein contacts the plush interior layer of the medical cast and is retained in a substantially stationary position relative to the medical cast.