Isotactic polypropylene (iPP) resin was doped with 1% of pimelic acid/calcium stearate (composition ratio = 1/1.5). It was crystallized in a two-step isothermal process, first at 130 degrees C and then at 95 degrees C, and finally cooled at a rate of 0.5 degrees C min(-1) to room temperature. The specimens were basically free of alpha-crystals and could be considered as pure beta-PP. The crystallinity of the specimens was determined on the basis of their density. The heat of fusion of the beta-crystal was found to be 168.5 J g(-1). In comparison, the heat of fusion of the alpha-crystal in the undoped resin was slightly higher at 177.0 J g(-1).