Freezer for biosanitary and cytotoxic waste, which comprises an inner space that houses a waste container, a front door through which the waste container in the inner space is inserted/removed, an upper door through which waste is poured into the inner container, cooling means and inner space temperature control means, wherein, the freezer further comprises an air purifier that treats an air stream coming from the inner space, when opening one of its doors, thus avoiding the emission of both chemical and biological particulate contaminants to the outside environment.