The embrittlement of 2 1/4Cr-1Mo steel by lithium or lead-lithium liquids can occur when loading conditions and microstructural strengthening effects limit plastic relaxation at points of high stress, and a critical liquid metal induced embrittlement (LMIE) stress is reached. This paper presents the LMIE results of both constant displacement rate uniaxial tensile testing and fatigue crack propagation studies. The temperature for the onset of LMIE susceptibility at a given localized strain rate is shown to be predictable based on a critical value of flow stress, calculated by means of the Zener-Holloman parameter.