Irradiation embrittlement of A533B steels with low copper contents were investigated from the point of dose rate and irradiation temperature effects. Change of neutron flux in the range from -10¹² to -10¹³ n/cm²/s (E> 1MeV) did not have a significant effect on the embrittlement. Irradiation temperature change of 1°C resulted in the transition temperature shift (ΔT^41J) of about 1°C and yield stress change (Δoy) of about 0.8MPa. Factors that might affect the embrittlement of low copper steels are also discussed.