We have prepared new DNA probes of various structures and examined their SNP discrimination abilities for target sequences of many transition and transversion SNPs of clinical importance, with the goal of the above-mentioned practical use in mind. As a result, we have developed a new electrochemical SNP typing system composed of synthetically feasible and versatile, cheap electro-active DNA probes. This system is expected to meet the criteria of the assay protocol required by end users majoring in clinical medicines. Further improvements of our methodology are in progress for realizing an ideal SNPs sensor.