We report a case of 'horseshoe-shaped' pressure-induced post-operative alopecia following a lengthy head and neck procedure. Post-operative hair loss is rare and to our knowledge has only previously been found in fields of surgery where careful head positioning is not an inherent part of the procedure. In these cases there has been a single area of hair loss from the central occipital area and per-operative pressure effects of the head resting on the operating table have been postulated as the likely cause. The case presented shows an area of hair loss closely corresponding to the shape of the head rest used during a long procedure. This strongly supports the theory that prolonged pressure is the likely cause. The mechanism of pathogenesis is discussed together with a suggested strategy for its avoidance. The single most important aspect of prevention of this complication of surgery is the knowledge of its existence and aetiology.