Device miniaturization is generally considered to improve the efficiency and throughput of instrumental chemical analysis. In this chapter, the power of miniaturization is examined from the viewpoint of microfabrication. Currently, microfabrication techniques are being increasingly applied to prepare fluidic arrays on silicon, glass, and polymer substrates with the final goal of realizing so‐called micro total chemical analysis systems (µTAS), also referred to as lab(oratory)‐on‐a‐chip. These miniaturized arrays aim at integration of multiple analytical unit operations on a single microfabricated chip (i.e., microchip), including sample preparation, injection, separation and detection. Sometimes reaction chambers are also implemented on the chip and integrated with on‐line sample preparation and/or separation systems. Although exploitation of microchip‐based analysis in small‐molecule analysis remains somewhat limited compared with proteomics, the vast potential of this technology is reviewed in the light of potential future applications in metabolomics. Often, examples are given to technological solutions which are not applied to metabolomics per se, but rather to related fields. Throughout this chapter, the emphasis is put on microchip electrophoresis (MCE) techniques. In addition, practical aspects related to pressurized methods, such as microchip liquid chromatography, are also presented. Microchip‐based off‐line and on‐line integrated sample clean‐up and preconcentration techniques are mainly touched upon where amenable to integration with a microfluidic separation system.