The present article discusses the antitrust regulation for reach-through royalty provisions which mainly used in biotechnology research tool patent licensing. First, this article introduces the meanings of research tool patent and reach-through royalties. Second, it illustrates antitrust regulations for patent licensing in foreign countries specifically in U.S., European Union, together with R.O.C. and, furthermore, it also discusses provisions similar or related to reach-through royalties. Third, this article introduces the discussions about reach-through royalty provisions in U.S., including the NIH Guideline, case law regulations and other related discussions by scholars. Finally, the present article analyzes the effects of reach-through royalties more deeply based on the mentioned discussions and makes a suggestion for the regulation of reach-through royalties. This article argues: since reach-through royalties have both anti-competitive and pro-competitive effects, a total ban or allowance is not appropriate and a “rule of reason” inspection should be applied to such provisions for better efficiencies.