In seeking a patent, applicants not only have to define the novelty of an invention but also have to indicate that such invention possesses an inventive step. Further, the patent application must thoroughly document the inventive step in the disclosure and claims. Failure to meet these criteria will lead to the dismissal of the application. The cases described in this article provide some important insights on how to avoid rejection of a Thai patent application due to inadequate attention to the requirements for inventive step.