TRIPS Agreement mandates adequate and effective protection for all inventions regardless of the field of technology. The fundamental questions are whether the extent of protection of pharmaceuticals will be beneficial for the socio-economic development of developing countries and how can the impact of the new system be monitored and controlled in the interests of the concerned countries and their populations. Under the Thai Patent Law, Section 46.50 provides for the grant of compulsory licenses, which in practical terms are difficult to implement so much so that no such licenses have been granted since 1979 when the Act came into force. Lack of know-how to work the patent in Thailand has also been a serious deterrent. Provision of a requirement for working of patented inventions is also part of the Thai Act. Section 36(2) of the Thai Patent Law authorizes parallel imports into Thailand if the products are marketed abroad by the patentee or his licensee. Section 9 (4) of the Act adopts the principle that methods of treatment are not patentable. Section 31 permits opposition to be filed after the application is published by the Patent Office. The implication of TRIPS and the Thai Patent Act on the pharmaceutical sector and on the patients in Thailand are discussed in this paper.