Spasticity is characterized by increased muscle resistance. It is usually associated with muscle weakness or poor motor control. This condition not only reduces activities of daily living (ADLs), but also interferes personal hygiere and causes caregiuer's difficulty. The use of botulinum neurotoxin (BoNT) intramuscular injections is a simple and effective therapy for spasticity. The use of BoNT to treat adult patients with spasticity was first reported in 1989, since then, using the neurotoxin to treat spasticity became popular in some European countries. Now in Japan, BoNT can be used to treat only torticollis, blepharospasm and hemifacial spasm because of the legal limitation on its use. However, clinical research on the use of BoNT in spasticity caused by stroke is presently underway, and an adaptation of the toxin may be available in the near future. This article reviews the characteristics of BoNT and the techniques for injecting this neurotoxin.