Purpose: To investigate the performance of different rotary instruments when machining cobalt-chromium alloy. Materials and Methods: One tungsten carbide bur, 1 diamond bur, and 2 aluminum oxide abrasive points (pink stones) of different diameter were used to machine cobalt-chromium alloy under standardized conditions. The rate of metal removal was determined and the resulting surfaces and bur wear were investigated using scanning electron microscopy and energy dispersive analysis. Results: Although the larger diameter pink stone was shown to be the most efficient instrument, the tungsten carbide bur produced the smoothest surface. Conclusion: Because of its low cost and high cutting efficiency, the pink stone is well suited for laboratory use. The tungsten carbide bur is the preferred instrument for clinical use.