In the last years, a growing number of fields such as air quality monitoring, breath analysis or explosives and chemical warfare agents detection requiring fast, on-site, sensitive analysis has led to the development of portable gas chromatography systems. In most cases, these systems integrate a miniaturized gas preconcentrator, which provides a significant enhancement of the sensitivity enabling quantification of analytes present in the sample at trace levels. In this review, the authors have focused on recent developments in these preconcentrators integrated in portable gas chromatography systems. The main materials and fabrication techniques, designs, heating technologies, fluidic connections, adsorbents, and applications are discussed. In addition, an analysis of some factors affecting preconcentration performance is presented. A new figure of merit called Normalized Preconcentration Efficacy (NPE) is proposed to evaluate the performance of these devices in a standardized manner, making possible a more straightforward comparison between different devices.