This study investigates the coupled effects of mild shear flow and temperature on the crystallization behavior of two thermoplastic polymers, namely, an isotactic polypropylene and an isotactic poly(I-butene). Rheological experiments are used to measure the crystallization induction time under isothermal, steady shear flow conditions. The experimental results clearly show the effects of the degree of undercooling on flow-induced crystallization (FIC). As temperature decreases, the corresponding increase in chain orientation at a given shear rate leads to an absolutely faster crystallization. At the same time, however, a temperature decrease makes the flow-induced driving force to crystallization relatively less influent with respect to the intrinsic kinetics. A FIC model based on the Doi-Edwards micro-rheological theory is shown to successfully describe the quantitative details of the observed experimental behavior. (C) 2004 Elsevier Ltd. All rights reserved.