We have studied the effect of shear rate on the very early stages of poly(epsilon-caprolactone) crystallization with in situ rheology and ex situ optical microscopy. The effect of shear rate is mainly to increase the nucleation density and to speed-up the crystallization process. Thermally-induced crystallization is separated from strain-induced crystallization allowing the construction of a 'master curve' indicating that the system obeys the shear rate-temperature-superposition. It was found that the free enthalpy difference in the melt G(m)((gamma) over dot,T) - G(m)((gamma) overdot = 0,T) increases with the shear rate ((gamma) over dot) that can be qualitatively rationalized by the reduced entropy of the melt prior to crystallization. (C) 2003 Elsevier Ltd. All rights reserved.