The workshop to review and plan therapeutic efficacy surveys (TES) to monitor P. falciparum and P. vivax resistance to antimalarial drugs in the Greater Mekong Subregion (GMS) happened in Sedona Hotel, Mandalay, Myanmar from September 30-October 2, 2009. The workshop had four objectives: 1. To review implementation of WHO TES protocol in all GMS countries against the WHO protocol and initial planning; 2. To review and consolidate results from TES in the GMS; 3. To develop regional and country work plans and budget of TES for the next two-year period (2010-2011); 4. To clarify relationship and harmonization of WHO supported in vivo TES with new related initiatives in the GMS.