Formation of fission gas bubbles heretofore has not been observed in uranium-aluminide fuels. Recent irradiations to record high burnups offered a possibility to determine the onset of fission gas bubble formation in this type of fuel. Present experimental evidence suggests that UAl2, UAl3, and UAl4 do not form fission gas bubbles at fission densities of 7 × 1021/cm3 of fuel (60% depletion of 93% enriched 235U), and that pure uranium aluminide is likely to remain free of fission gas bubbles to very high 235U burnup at any enrichment. However, fission gas bubbles were found in these experimental fuels for the first time, but they were without exception associated with uranium-oxide inclusions that were evidently formed during fuel fabrication.