The Wellcome Trust-Mahidol University-Oxford Tropical Medicine Research Programme (the ‘Thailand Unit’) began in 1979 as a research collaboration between the Faculty of Tropical Medicine, Mahidol University and the University of Oxford. The main administrative office and laboratories are embedded within the Faculty, though most clinical studies and much laboratory work takes place in ‘up-country’ study sites. MORU’s main research interests are the epidemiology, diagnosis, pathophysiology and treatment of malaria, scrub typhus, melioidosis, leptospirosis and other tropical infections that impose a substantial disease burden on rural populations throughout this populous region. In addition to SMRU in Mae Sod and the Laos Project, the Unit has study sites in Ubon Ratchatani (melioidosis and cryptococcal meningitis), Udon Thani (scrub typhus and leptospirosis), Mae Sod Hospital (malaria and microbiological support for the Shoklo Malaria Research Unit (SMRU; website: http://www.shoklo-unit.com), Chittagong Medical College in Bangladesh (severe malaria), and Rourkela in India (severe malaria). The Unit also supervises severe-malaria clinical-trial sites in Burma.