Heterotopic ossification is a well known complication in patients after longterm coma following CNS trauma. The association of heterotopic ossification and a nerve compression syndrome situated near the calcifications is less common. The authors present 2 CNS traumatised patients who secondarily developed the association of heterotopic ossification of the elbow with a compressive syndrome of the ulnar nerve. Although heterotopic ossification does not appear to be the direct cause of the nerve compression, it certainly promotes compression it because of the flexion it causes.