Eight species of Isotomiella Bagnall, five of which are new, are recorded from Thailand: I. symetrimucronata Najt & Thibaud, 1987, I. nummulifer Deharveng & Oliveira, 1990, I. cribrata Deharveng & Suhardjono, 1994, L brevidens sp. n., I. edaphica sp. n., I, hirsuta sp. n., I. inthanonensis sp. n., and I. leksawasdii sp. n. Isotomiella minor (Schaeffer, 1896), the only species previously recorded from Thailand, is probably misidentified. A key to the species of Thai Isotomiella is given.