The objective of the present work was to search for methodological options facilitating the improvement and optimization of the biological microchip designed for genotyping of the AB0 locus. Testing a prototype biological microchip for genotyping of the AB0 locus using a reference set of preparations with the known group specificity has demonstrated that the choice of DNA probes by theoretical calculation of their thermodynamic parameters does not necessarily yields the desired practical result. Suffice it to say that under certain conditions some cells of the biochip appear to generate artifact hybridization signals that tend to make the results of genotyping either incorrect or difficult to interpret. This problem required the adjustment of the molecular structure of DNA probes for the optimization of their hybridization properties. As a result new DNA probes have been developed and synthesized and new variants of the prototype biochip constructed to be subjected to experimental verification.