Synanthropic fly surveys were performed to determine the species composition and abundance in Ubon Ratchathani province in Northeast Thailand. Adult fly collections were conducted in various human habitations from two districts-Muang Ubon Ratchathani and Warinchamrap, at fresh-food markets, garbage piles, restaurants, school cafeterias, and rice paddy fields. Customized reconstructable funnel fly traps baited with 250 g of 1-day tainted beef were used for fly collections from September 2010-February 2011. A total of 3,262 flies were captured, primarily consisting of three families including: Calliphoridae (6 species), Muscidae (3 species), and Sarcophagidae (11 species). The blow fly, Chrysomya megacephala, and the house fly, Musca domestica, were the dominant species collected from both districts at all collection sites. C. megacephala was predominant in paddy fields, restaurants and garbage piles, while M. domestica was numerically dominant in fresh-food markets and school cafeterias. The current survey identified various species of synanthropic flies with close associations to humans and with the ability to transmit human pathogens in Ubon Ratchathani province; providing crucial information that may be used for developing control and sanitation management plans in this particular area.