To ensure the clinical value of medical interventions, randomized controlled trials (RCTs) are necessary. However, the results of conventional RCTs cannot show individual therapeutic efficacy and safety for medical intervention to a targeted patient. It is the most important weak point of conventional RCTs. Here I show that the new clinical research method by using human induced pluripotent stem (iPS) cells technology will be able to complement the most important weak point of conventional RCTs. As the representative examples, I show the new clinical values of statins (inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase) found by using human iPS cells technology in achondroplasia or hanatophoric dysplasia (type 1) case and hepatitis C virus (HCV) infection case. Furthermore, they are also important examples for drug repositioning. Therefore, my article would be valuable as a scientific communication for physicians and/or scientists.