Meiofauna is an important component of coral reef ecosystems however data from scientific research concerning coral reef meiofauna in Thai waters are relatively limited. This study focused on composition and abundance of meiofauna in coral communities from 20 study sites at Ko Kut-Ko Mak, Trat Province and Mu Ko Samed, Rayong Province, in the Eastern Gulf of Thailand and Mu Ko Angthong, Surat Thani Province, in the Western Gulf of Thailand. Benthic composition of coral communities at the study sites in Ko Kut-Ko Mak and Mu Ko Angthong mostly covered by dead corals, except the study site at Kong Hin Ao Salad with live coral cover up to 71% and the study site at Hin Dap with live coral cover up to 65%. The results revealed that the highest total density of meiofauna was found at Mu Ko Samed, following by Ko Kut-Ko Mak, while the lowest one was recorded at Mu Ko Angthong.