Fuel particles coated with pyrolytic carbon are contemplated for use in several high-temperature gas-cooled reactors. This paper describes the performance of pyrolytic carbon-coated, high-density, uranium oxide particles irradiated at 1300 to 1600°C. The fission-gas release, burnups, and temperatures for five experiments are given. Coated particles with a builtin gap between the fuel and the inner laminar coating began to show evidence of failure by releasing bursts of fission gas after 27.9% uranium burnup, and postirradiation examination revealed delamination of the inner coating. Coated particles made with a porous carbon buffer layer between the fuel and an isotropic coating showed no evidence of failure by fission-gas release, and showed no damage due to irradiation when examined by metallography. Coated particles with neither gap nor buffer, but with a low-density inner coating applied directly to the fuel, retained fission gas successfully but showed enlargement of cracks that had formed at the fuel-coating interface during the coating process. The oxide particles did not flow at high burnup and expand into voids and cracks as the carbide particles did, and the oxide did not diffuse into the carbon coating at high temperatures.