This paper describes a novel disposable and portable plastic-silicon polymerase chain reaction (PCR) system using microfabrication technologies for the realization of miniaturized nucleic acid analyses. The system consists of a polyimide-based film microheating system, embedding with a microheater and a temperature sensor made entirely with flexible printed circuit board (FPCB) process protocols, and a bulk-micromachined silicon reaction chamber. Reduction of the thermal mass by employing a 25 mum-thick polyimide film substrate, which has chemical and thermal resistance suitable for photolithography processes, and integration of a temperature sensor as well as a heater on the film facilitates rapid and precise temperature control. The microfabricated PCR chip demonstrated precise heat control and rapid thermal response in the chip. In addition, the chip successfully amplified a genomic DNA template (breast cancer suppressor gene, BRCA 1 127 base pairs), extracted from the human whole blood containing approximately 100 copies in a 3 muL-volume chamber within 18 min. Thus, it is applicable to a portable system for precise, fast, efficient and cost-effective nucleic analysis, and can be utilized with microscale biochemical analysis and sensing systems as well.