The number of characterized monogenic and polygenic diseases is rising each year. In consequence, molecular diagnostics is faced with an ever increasing number of patient samples and with more and more heterogeneous genetic defects. The fusion of microelectronics and molecular biology has created a new technology (microelectronic miniaturization), which provides a rapid, efficient, and cost-effective tool in molecular diagnostics at a high-sample throughput. The biochip has recently been selected as one of the ten scientific highlights in the year 1998. The application of microelectronics ranges from the polymerase chain reaction (PCR), nucleotide sequence analysis via DNA-chips or capillary electrophoresis-chips to gene expression analysis. These microchips are suited for integration into fully automated systems, thus providing the basis for automation of molecular diagnostics. The present article summarizes important trends in molecular diagnostics and provides a glimpse on future technologies.