In general, a patent examination result obtained in one country should be deemed as valid in other countries for the same technology. Many countries have included this principle in their patent laws. However, the same invention has to go through substantive examination separately on a country-by-country basis. Each country has a different approach to what the examination entails and whether or not the requirements of patentability have been met. Therefore, an application which has already been granted in another country may not necessarily be patentable in Thailand. The case described in this article provides an illustration of how country-by-country examination differences can impact a patent application.