A rectrospective study of 23 consecutive patients with hemifacial spasm is presented. Based on this experience, a practical approach to the diagnosis, investigation and treatment with injections of botulinum toxin is described. Magnetic resonance imaging angiography of the brain was performed in 20 patients an 15 controls. Contact between an artery from the vertebrobasilar circulation and the intracranial part of the facial nerve was observed ipsilaterally to the spasm in 17 patients (85%) and in two controls (7%). Treatment with botulinum toxin was performed in 16 patients with moderate to good improvement in the majority of the patients. MR-angiography is recommended in order to exclude infrequent etiologies and as preoperative evaluation. Botulinum toxin injection is recommended as the symptomatic treatment of choice. The possibility of curative surgical intervention by microvascular decompression of the facial nerve is discussed.