For the past decades, opium-based drug was the most threatening drug abuse in the Greater Mekong Sub-region, Thailand and UN have begun mutual cooperation on drug control since 1972. Numbers of drug control projects, i.e., alternative crop replacement programmes, highland development programmes, drug prevention & rehabilitation programmes, human resource development programmes and technical researches have been complied. Over US$ 16 millions had been applied to those programmes in Thailand. 20 years later, drug supply reduction programmes in the highland were outstandingly accomplished. The opium production had been reduced over 27 times, from 150 tons in 1974 to 5.5 tons in 1994. Its cultivation area had been sharply decreased from 20,744 hectares in 1974 to 748.8 hectares in 1994. Since 1994, there was none of Thailand-UN highland development proposal had been granted. However, drug control in the highland is not over. Thai authorities, especially, the Royal Highland Project still keeps on their paths for sustainable drug-free communities.

Thailand-UN drug control cooperation has been abiding by the following protocols:
- UN Conventions
- Single Convention on Narcotic Drugs 1961 as amended by the 1972 Protocol
- Convention on Psychotropic Substances 1971
- Convention against Illicit Traffic in Narcotic Drugs and Psychotropic Substances 1988
- Related UN Agreement / MOU / Treaty / Declaration

Most of mutual Thailand-UN cooperation has been complying through UNOCD Regional Centre for East Asia and the Pacific in Bangkok. In 1972, UN field office on drug control had been established in Thailand. In 1991, the United Nations International Drug Control Programme (UNDCP) Regional Centre had been established in Bangkok.

The United Nations International Drug Control Programme (UNDCP) has been renamed the United Nations Office on Drug Control and Crime Prevention (ODCCP), effective 1 November 1997.

The United Nations Office on Drug Control and Crime Prevention (ODCCP) has been renamed the United Nations Office on Drugs and Crime (UNODC), effective 1 October 2002.

At present, Thailand has committed US$ 10,000 annual donation to UN.

Besides, Thailand – UN cooperation on drugs also comply under 1993 MOU (7-party) and ASEAN and China Cooperative Operations in Response to Dangerous Drugs (ACCORD) umbrellas.