Category 1 Continuing Medical Education credit for physicians is available to Wilderness Medical Society members for this article. Go to http//wms.org/cme/cme.asp?whatarticle=1813 to access the instructions and test questions.Objective.—Experimental data indicate that when using a sit harness alone, any major fall during rock climbing may cause life-threatening thoraco-lumbar hyperextension trauma or “head down position” during suspension. To clarify the actual influence of the type of harness on the pattern and severity of injury, accidents involving a major fall in a climbing harness were analyzed retrospectively.Methods.—Individuals with a height of fall equal to or exceeding 5 m were identified through a search of accident and emergency records for the period from 2000 to 2004. Data concerning the circumstances of the fall and the patterns of injury were obtained from personal interviews, flight and accident reports, as well as hospital medical records.Results.—Of a total of 113 climbers identified, 73 (64.6%) used a sit harness alone, whereas 40 (35.4%) used a body harness. Fractures and dislocations of the extremities, the shoulder, and the pelvic region were the most common injuries, while the most severe injuries occurred in the head and neck region. Although most falls were associated with mild or moderate injuries, 13 (11.5%) climbers sustained severe or critical multisystem trauma. Falls on more difficult routes were associated with less severe injury. The type of harness used did not influence the pattern or severity of injury. In particular, no evidence was found for the existence of a thoraco-lumbar hyperextension trauma.Conclusions.—The type of harness does not influence the pattern or severity of injury, and the forces transferred via the harness do not cause a specific harness-induced pathology. We did not find any evidence that hyperextension trauma of the thoraco-lumbar region is an important mechanism of injury in climbers using a sit harness alone. Rock contact during the fall, and not the force transferred through the harness, is the major cause of significant injury in climbing accidents.