Low cycle fatigue (LCF) behavior of an A533B-type low-alloy pressure vessel steel was investigated in 200 degrees C and 288 degrees C water. Major attention was paid to the role of dynamic strain aging (DSA) on corrosion fatigue behavior of the steel. It was found that DSA played a noticeable role in the present corrosion fatigue process, manifested by the strain-rate and temperature dependent cyclic stress and plastic strain amplitude response. DSA was found to occur at a low strain rate in 200 degrees C water or at a high strain rate in 288 degrees C water regardless of dissolved oxygen concentration (DO) in water. In low-DO water, DSA improved the LCF resistance of the steel to some extent, but such an effect was screened by the environmental effects in high-DO water. The interactions between DSA and surrounding environmental factors as well as their possible influence on environmentally assisted cracking and fatigue resistance of the steel in high temperature water are discussed.