Within the last decade protein microarray technology has been successfully applied for the simultaneous identification, quantification and functional analysis of proteins in basic and applied proteome research. These miniaturized and parallelized assay systems have the potential to replace state-of-the-art singleplex analysis systems. However, prior to their general application in robust, reliable, routine and high-throughput applications it is mandatory that they demonstrate robustness, sensitivity, automation and appropriate pricing. In this review, the current state of protein microarray technology will be summarized. Recent applications for the simultaneous determination of a variety of parameters using only minute amounts of sample will be described and future challenges of this cutting-edge technology will be discussed.