INTRA-ARTICULAR and intramuscular hemorrhages are well recognized as frequent causes for disability in patients with hemophilia. Another less common cause for impaired motility of an extremity in a hemophiliac is involvement of a peripheral nerve by hemorrhage. The purposes of this communication are to report the incidence and nature of the peripheral nerve lesions observed in 206 patients with hemophilia; to review the pertinent literature; and to discuss briefly the pathogenesis, management, and prognosis of this somewhat neglected complication of hemophilia. Materials and Methods The 206 hemophiliacs were all admitted to the Mount Sinai Hospital, New York. The criteria employed for the diagnosis of hemophilia have been presented elsewhere.1 Deficiency of factor IX (plasma thromboplastin component) was demonstrated in 17 patients and of plasma thromboplastin antecedent (factor XI) in 6. The remainder were deficient in factor VIII (antihemophilic factor) or were hospitalized at a time when facilities for determining