A bias in spontaneous turning has been observed in several animal species, at the individual or group level. There has been no consensus so far on the existence of such a bias in humans, probably due to lack of control of the factors likely to modulate this bias. We tested the spontaneous behavior of thirteen human adults required to run around a circle in an empty, symmetrical space, as a function of starting position (from the left, the center, or the right), and gaze direction (to one of five targets going from left to right). A clear significant overall tendency to turn counterclockwise across all conditions was observed. This was particularly striking when the participants were required to start from the center position and look straight ahead before starting, with more than 80% of the participants turning counterclockwise in this perfectly symmetrical condition. Starting position, gaze and head direction modulated the bias, without masking the counterclockwise tendency. We discuss some of the factors likely to be partly responsible for this clear turning bias, including cognitive space representation, and preference for keeping the peripheral vision to one's left visual field during running due to hemispheric asymmetry.