We describe a case of a 65-year old patient diagnosed with amyotrophic lateral sclerosis. The clinical findings, with symmetric, predominantly proximal wasting and weakness of both arms (especially of the infra-, supraspinatus and deltoideus) leading to severe functional disability and contrasting with preserved independent ambulation and sparing of bulbar muscles, were consistent with the proposed criteria of the so-called flail arm syndrome. Based on our case we characterize the clinical features of flail arm syndrome and review the literature.