Author analysed cholecystosonographic findings in 22 patients with clonorchiasis, suspected prospectively byultasound and proved subsequently by demonstration of eggs in the stools. Fifteen gallbladders had non shadowing, fusiform, discrete echogenic foci measuring 3-6mm in the lumen. Among these, the echogenic foci floated spontaneously in three cases, while in twelve cases they floated by position change or a light blow by the transducer, In the rest of the seven gallbladders, the echogenic foci were at the dependent portion. In the in vitro study with a worm suspension in saline in a surgical glove, the same echogenic foci as those seen in the gallbladder were demonstrated. The echogenic foci were precipitated in the dependent portion but float with alight blow on the glove. Author conclude that the floating echogenic foci in the lumen of the gallbladder are dueto adult worms of Clonorchis sinensis.