Thirty-five blood group systems, containing more than 300 antigens, are listed by the International Society of Blood Transfusion (ISBT). Most of these antigens result from a single-nucleotide polymorphism (SNP). Blood group typing is conventionally carried out by serology. However, this technique has certain limitations and cannot respond to the growing demand for blood products typed for a large number of antigens. Here we describe a blood group genotyping assay, from genomic DNA extraction from whole-blood samples to results. After DNA extraction, the on-chip test is based on the hybridization of targets beforehand amplified by multiplex polymerase chain reaction, followed by a revelation step allowing the simultaneous identification of up to 24 blood group antigens and leading to the determination of extended genotypes.