The echolocating ability of short-tailed shrews was investigated by training them to select an open tube over a closed tube through which to run. With the elimination of other sensory possibilities, and by recording the ultrasonic “clicks” emitted by the shrews, it was verified that this discrimination was made via echolocation. The shrews could distinguish between open and closed tubes up to 61 cm in length. At 30.5 cm this distinction was possible for openings as small as 0.63 cm in diameter, and around corners up to 90°. The shrews could also make some distinctions between different materials.