The U.S. Food and Drug Administration has granted Edaravone (Radicut, MCI-186) Orphan Drug Designation for the treatment of amyotrophic lateral sclerosis (ALS). Edaravone is a free radical scavenger and a potent antioxidant marketed in Japan by Mitsubishi Tanabe Pharma, a Japanese pharmaceuticals company headquartered in Osaka, Japan. ALS is a rare neurological disease characterized by progressive death of motor neurons leading to problems with muscle control and movement, and eventually death. The majority of ALS is sporadic and only 5-10% is hereditary. The cause of ALS is still unclear and there is no cure currently available. Edaravone has been shown to function as a neuroprotective agent and clinical studies have also demonstrated its efficacy in improving neurological symptoms in patients at acute stage of cerebral infarction. Mitsubishi Tanabe is currently conducting phase III clinical trials evaluating the efficacy and safety of Edaravone in ALS patients.