Horizontal-canal benign positional vertigo (HC-BPV) is characterized by brief attacks of intense vertigo that are induced by mainly rolling over in bed. Examination shows a burst of purely horizontal nystagmus beating toward the undermost ear when the head is turned from supine to either lateral position. Two patients with typical HC-BPV were treated by a new positional procedure that aims to clear particles from the affected canal. The maneuver starts with the patient in the supine position and consists of three 90-degree head rotations toward the unaffected ear. Both patients had immediate and sustained relief of their attacks. No positional nystagmus could be elicited after the maneuver. The rapid cessation of positional vertigo and nystagmus adds evidence that HC-BPV is caused by dense particles that move within the canal whenever its orientation toward gravity is changed.