We have investigated the influence of scanning rate on the form of DSC melting curves in semicrystalline polymers in which the melting point varies spatially within the sample. A numerical solution for the heat balance in the sample cell was used, taking into account heat absorbed during the melting transition for a given sample mass. The simulation accounted well for the effects of scanning rate on the shape of the DSC peak for polyoxymethylene samples crystallized above 150 degrees C, which were assumed to be free from effects arising from lamellar thickening during the scan.