The cost of control rods which contributes a significant fraction to the total cost of a power reactor core is discussed as a function of metallurgical composition and reactor endurance. Materials considered include hafnium, Cd5-In15-Ag80 alloy, several boron carrying systems, and dispersions of such rare earth oxides as Eu2O3, Gd2O3, and Dy2O3. Costs based on a thorough analysis of processing variables and raw material prices are presented for a variety of rods for a specific reactor design considered typical of enriched power plants of the present generation. Concentrations were established by an approximate method described by Stevens. Although this method is relatively crude, results are considered adequate for purposes of this paper. For long-lived cores the lowest cost rods of proven composition were a composite rod with hafnium tip and boron dispersion upper blade or hafnium rods if the hafnium can be bought at presently quoted zirconium co-product prices. Rare earth cermets of properly adjusted composition also fell into an interesting price range. Boron dispersions though lower in cost cannot be considered among the proven materials for long-lived high burn-up cores. For shut down rods or cores of shorter endurance boron steels offer a low cost solution to the problem. For cores of intermediate endurance or shut down rods for longer endurance cores, Cd-In-Ag alloy rods may be of use and are certainly economically attractive.