Kinetic theory of crack growth is used to predict the residual strength of polymetric materials acted upon by a previous history. Specifically, the kinetic theory is used to characterize the state of growing damage that occurs under a constant‐stress (load) state. The load is removed before failure under creep‐rupture conditions, and the residual instantaneous strength is determined from the theory by taking account of the damage accumulation under the preceding constant‐load history. The rate of change of residual strength is found to be strongest when the duration of the preceding load history is near the ultimate lifetime under that condition. Physical explanations for this effect are given, as are numerical examples. Also, the theoretical prediction is compared with experimental data.