HLA Typing on Microarrays. Microarrays can perform thousands of DNA hybridization reactions in parallel: many more than required to produce a high-resolution HLA-Type. However, their cost and complexity has been prohibitive as an HLA-Typing test. Our aim is to produce high-throughput HLA microarray tests and software which are simple and inexpensive enough to become a new standard in transplantation testing and immunogenetics.We have developed an HLA-Typing test, comprising 576 oligonucleotide probes printed as twelve [24×24] microarrays on a 1″× 3″ glass slide: so that 12 DNA samples can be analyzed in parallel. Five tests have been developed [A, B, C, DRB1] and a “Combo” test where all four microarrays are printed on a single slide. These tests all use as ligand, the product of a specialized PCR reaction, modified to accommodate impure (or raw) DNA-containing samples, thereby mitigating the effects of DNA sample impurity or imprecise DNA quantitation.We have used UCLA Exchange proficiency testing standards, over a range of DNA sample concentration from 1ng to 30ng and in the presence of added impurities, to show that these 5 HLA-Chip tests can generate HLA-Types at 4-digit resolution, with concordance approaching 100% with respect to a set of 36 UCLA standards. It is shown that, by implementing recent technical advancements, the hybridization reactions can now be completed in 2-h, with all post-PCR manipulations being performed at the bench, at room temperature, followed by automated data analysis.We demonstrate validation of HLA-Typing as a simple, fast, bench-top testthat can be performed with little specialized equipment or training. Resolution obtained via these HLA-Chip tests is found to be solidly in the 4-digit resolution category. Based on scale-up now in progress, the 5 HLA-Chip tests can now be sold as a “kit” product at a price that meets, or is lower than that currently seen for bead-based assays, or HLA-Typing by allele specific PCR.