ABSTRACT: Botulinus toxin (BTX) is the most potent biological toxin yet known. It is produced by Clostridium botulinium, a Gram positive bacteria. Type A Botulinus toxin is the most widely used in human drug trials. It has become the treatment of choice for blepharospasm, hemifacial spasm, cervical dystonia and laryngeal dystonia. It may also be used in the treatment of patients with oromandibular dystonia and limb dystonia, specially writer’s cramp, and has been used successfully in the treatment of spasticity and cerebral paralysis. There are many benefits from this treatment, including improved walking, improved posture of wheelchair patients, improvement of patients with spasms and easier extension of their arms and knees. The toxin also alleviates pain and may be used in therapeutic trials for prediction of the response to surgical elongation.