A brief history of the development of the rotating cage as a promising and reliable laboratory methodology for inhibitor evaluation is presented. The influence of the geometry of the rotating cage on the flow pattern as well as on corrosion rates has been investigated. The importance of vessel length and diameter, rotating cage length (and, as a consequence, the sample length), rotating cage diameter, rotation speed, volume of liquid, and flow pattern in determining the corrosion rates, and hence, inhibitor efficiency has been established.