Since the beginning of 2000, molecular-targeted therapy was introduced mainly in the clinical oncology fields. Based on the results of molecular biological analyses on cancer evolution and progression, various drugs targeting key molecules involved in cancer cell proliferation, invasion and metastasis have been developed and examined. As expected, they showed very sharp effects in the suppression of tumor growth. Simultaneously, they sometimes showed mechanism-based adverse effects in particular tissues. In Japan, there have been many promising trials to develop novel molecular-targeted therapy. Application of results of glycobiology for these trials also seems promising. "On-target" side effects and prediction of drug-sensitivity are now urgent issues to be discreetly solved.