Botulinum toxin type A has been used clinically for the prophylaxis and treatment of various types of primary headache disorders for over 15 years. Several studies have been performed to demonstrate its mechanism of its effect. There is adequate data to support the idea that; beside its well-known effect on acetylcholine release, an additional antinociceptive effect related to a possible block in one or more pain transmitters exists. Earlier open-labeled studies investigating the clinical outcome of botulinum toxin in primary headache disorders have come out with positive results on the topic however recent evidence based evaluation of data do not seem to support the widespread clinical use of this agent. In this manuscript use of botulinum toxin is reviewed with special emphasize on its mechanism of effect, injection techniques and recent evidence-based data.