Calculations to determine the influence of different schemes for the utilization of recycle fuel on High-Temperature Gas-Cooled Reactor (HTGR) fuel cycle costs showed that commercial reprocessing of spent fuel should begin in 1984 or 1985 for the reactor construction schedules assumed. A benefit-to-cost ratio for recycle research and development work was computed and ranges from ∼10 to 70, depending on the penetration of the HTGR into the U.S. power generation economy. The presently planned introduction of commercial reprocessing capability in 1985 will result in nearly optimum fuel cycle costs. However, substantial delays beyond this data will result in sizable cost penalties, with the magnitude of the penalties increasing with increasing HTGR market penetration.