Flail arm syndrome (FAS), an atypical variant of amyotrophic lateral sclerosis (ALS), is characterized by progresses slowly, predominantly proximal, weakness of upper limbs, with no involvement of the lower limb, bulbar, or respiratory muscles. In the world, 1-3 cases per 100,000 people per year are registered. Incidence is higher among whites. The peak age is 55-75 years, although it can occur at a younger age. The male gender is dominant. Signs of upper motor neuron (UMN) lesions of the cervical region in flail arm syndrome patients are rare. The lack of information regarding FAS may make differential diagnosis between flail arm syndrome, upper limb onset amyotrophic lateral sclerosis and other lower motor neuron syndromes difficult in clinical settings. The prognosis of FAS is better than that of upper limb ALS and most cases of FAS are sporadic. Therefore, a reliable differential diagnosis is essential to determine the prognosis. Compared with the other varient of ALS, clinical symptoms progress over a relatively long period of time in flail hand syndrome, with a median survival of 4 years and a 10-year survival of 17%. We report a 79 year old patient admitted to the hospital with a 1 year history of proximal weakness and 2 arm shoulder girdle muscle stiffness, wasting and 2 arm m.deltoideus fasciculations with Flail arm syndrome. It was one of the few cases of arm drooping syndrome, which begins only with weakness, stiffness, and symmetry in the proximal part of the upper limbs. Definite ALS was diagnosed based on clinical examination /neurological abnormalities/ and electromyography results.