The factors affecting fuel cycle costs for research reactors are reviewed and discussed. An analysis and comparison is made of the costs associated with operation at 5 MW of U-Al- and UO2-fueled reactors. A similar analysis and comparison is made for 1-MW operation of U-Al-, U-Zr-H-, and UO2-fueled reactors. Costs are plotted for operations over the power range of 1 to 5 MW and for utilization levels of 8, 16, and 24 h/day. Results indicate that U-Al fuel is most economic at low power and low utilization, and that UO2 has a decided economic advantage above 250 to 300 MWd/year.