Integration of the whole operations enabling gene expression analysis on microchips is a rather recent advance in the â rather young â world of microfluidics. Here, we summarize the gradual evolutions that led from the very first â millifluidicâ integrated chip for RNA analysis to more sophisticated and sensitive devices. We show how the developments of an initially applied problematic (creating portable integrated devices for e.g. point of care analysis) are finally used for studies of fundamental importance in cell biology. Two main families of devices are found in the literature: those integrating multiple steps to carry out RNA reverse transcription and DNA amplification separately, and those that take advantage of the recent developments of biology chemicals to perform RNA analysis in a single step. The latter are generally highly sensitive, and single cell RNA analysis has been made possible in very low volume handling systems. Nevertheless, in contrast to some other microfluidics biological applications, there remains room for progress in miniaturized gene expression analysis. Further efforts are still needed to provide reliable tools for use in applied biology as well as in fundamental research.