Extensive toxicological studies of polydimethylsiloxanes, popularly referred to as “silicones,” have shown that these materials rank among the least hazardous of all industrial materials. Nonetheless, adoption of silicone brake fluids by only a portion of the automobile industry could result in appreciable environmental imposition, thus posing a potential ecological problem. Considerations such as toxicology, biodegradability, disposal or reuse, and effects on manufacturing personnel and processes are as important as the more visible performance parameters, and must be resolved satisfactorily. These topics are the subject of this paper.