Inter Partes Review (IPR) is conducted at the Patent Trial and Appeal Board (PTAB) to review the patentability of claims only on the basis of anticipation and obviousness based only on patents or printed publications. So far, more than 70 percent of petitions have resulted in instituting of an IPR. This article discusses best practices for petitioning for an IPR and how it can be a very attractive route for potentially invalidating patent claims for generics which do not have the 180-day market exclusivity incentive