Compact-tension (CT) specimens of stainless steel DIN 1.4948, which is similar to AISI Type 304, have been irradiated up to a fluence level of 2.10²⁴ n.m.⁻² (E > 0.1 MeV) at temperatures ranging from 330 to 823 K. Post-irradiation constant-load-amplitude crack propagation (fcp) tests were performed in air at temperatures from 298 to 823 K with frequencies ranging from 10⁻³ to 10 Hz and R-ratios (min. load/max. load) of 0.05 and 0.30. Irradiation hardening after the low temperature irradiations (573 K and below) caused a reduction of the fatigue crack growth rate. Irradiation at the higher temperatures did not affect the fcp at the high frequency of 10 Hz. At 823 K the combination of high R-ratio and low frequency (10⁻² Hz) resulted in an increase of the post-irradiation crack growth rate with a factor 10. This irradiation effect is attributed to the observed intergranular crack propagation.