Classical methods of protein analysis such as electrophoresis, ELISA and liquid chromatography are generally time-consuming, labor-intensive and lack high-throughput capacity. In addition, all existing methods used to measure proteins necessitate multiple division of the original sample and individual tests carried out for each substance, with an associated cost for each test. The chip system allows several tests to be performed simultaneously without dividing the original patient sample. This system facilitates the development of multiplexed assays that simultaneously measure many different analytes in a small sample volume. These emerging technologies fall into two categories: 1) spotted array-based tools, and 2) microfluidic-based tools. Miniaturized and multiplexed immunoassays allow a great deal of information to be obtained from a single sample. These analytical systems are referred to as "lab-on-a-chip" devices. This article presents current trends and advances in miniaturized multiplexed immunoassay technologies, reviewing different systems from research to point-of-care assays. We focus on a subset of chip-based assays that may be used in a clinical laboratory and are directly applicable for biomedical diagnosis. Recent advances in biochip assays combine the power of miniaturization, microfluidics, micro- to nanoparticles, and quantification. A number of applications are just beginning to be explored. The power of biochip assays offers great promise for point-of-care clinical testing and monitoring of many important analytes.