Using a conventional hot-filament chemical vapor deposition system, diamond crystals and films were deposited on diamond-like carbon (DLC) films which were synthesized from a [C6H5C](n) polymer on silicon substrates under a temperature of 1000 degrees C in an argon atmosphere. The nucleation density of the diamond on DLC-Si substrates was estimated to be about 10(8) to 10(10) cm(-2), equivalent to or higher than the best values for scratched silicon substrates. During the deposition process, most of the amorphous carbon phases of the DLC films were etched away, while most of the crystalline carbon phases remained, and homoepitaxial growth on the crystals in the DLC films was observed which suggested that the amorphous phase mainly consists of sp(2)-hybridized carbon and the crystalline phase mainly consist of sp(3)-hybridized carbon. It is proposed that the diamond phase carbon (sp(3) carbon) of the DLC films act as a nucleation site and enhances the diamond nucleation.