The high-temperature gas-cooled reactor is a flexible system. The all- ceramic core permits high outlet temperatures compared to other reactors; thus, it is possible for the HTGR to be used with both steam cycle and gas turbine generating equipment. Also, the HTGR can be used as a source of high-temperature process heat. Core outlet temperatures of 700$sup 0$C are now available for the steam cycle. For very advanced HTGRs, temperatures as high as 1000$sup 0$C may be expected. HTGR fuel designs have a number of variations of geometry, fuel composition, and nonnuclear structural materials. Fuel cycle possibilities include the low-enrichment cycle and the Th-$sup 233$U cycle; with plutonium utilization in either cycle. All of this flexibility complicates the fuel design and fuel cycle technology for the reactor. This paper examines the complexities involved, emphasizes the status of fuel development and fuel cycle technology, and projects what may be possible in future applications. (auth)