Introduction. Botulinum toxin is produced by the anaerobic bacterium Clostridium botulinum. The sporulation form of the C. botulinum is widely found in the environment (in soil) and may develop in inappropriately stored food. The symptoms of poisoning occur 18-36 hours after consumption of contaminated food. Aim. The aim of this study is to present the benefits of using botulinum toxin in the treatment of spasticity of the upper and lower limbs in both adults and children. Material and methods. A literature review of the following databases was carried out: PubMed, UpToDate. Results. Botulinum toxin interferes with neural transmission by blocking the release of acetylcholine and causes muscle paralysis. The typical symptoms are diplopia, xerostomia, enteroparesis, speaking and swallowing disorders, as well as paralysis of respiratory muscles which leads to death. However, botulinum toxin is also a very potent medication. The biggest application is found in the field of neurology, inter alia, in the treatment of spasticity. Conclusion. The study provides current evidence regarding the safety and efficacy of botulinum toxin injection for spasticity of the upper and lower limbs. Botulinum toxin injections are applicable in the treatment of many neurological disorders and the list of indications will certainly become wider.