Morphological and acoustic comparisons were made for three morphologically poorly defined Microhyla species, M. ornata, M. fissipes, and M. okinavensis on the basis of samples from south India, Taiwan, and three islands (Iriomotejima, Okinawajima, and Amamioshima) of the Ryukyu Archipelago, Japan. These three species differed from each other in various external characters, and could be separated by multivariate discriminant analyses. Mean SVL of males was significantly smaller in M. fissipes than in M. ornata and M. okinavensis. The length of the hindlimb relative to SVL increased from west (India) to east (Amamioshima). Microhyla ornata showed a remarkable diurnal-nocturnal color change and had more extensive mottling on the throat and venter than the other two species. The Iriomotejima population of M. okinavensis had a unique ventral mottling pattern that differed from the patterns in the other two conspecific populations examined, as well as from those in M. ornata and M. fissipes. Excepting the Iriomotejima population, M. okinavensis had more extensive toe webbing than M. ornata and M. fissipes. Temporal acoustic features, especially pulse repetition rate, clearly discriminated the three species. The taxonomic status of the Iriomotejima population deserves future investigation.