A study of modeling heat transfer with crystallization in thick rods is described. We apply a formulation due to Nakamura et al. and Berger and Schneider to determine the temperature pro files through a thick rod. This involves a non-homogeneous cylindrical coordinate heat conduction equation with a heat of crystallization source term. The partial differential equation describing the temperature profile is represented in terms of dimensionless groups characterizing the ratios of heat of crystallization, surface heat transfer and thermal inertia to heat conduction. These dimensionless groups are used to characterize the solutions of this equation. Different solution regimes are predicted. The application to radial temperature profiles during melt spinning of polymer filaments is described.