Hemifacial spasm (HFS) resulting from Chiari type I malformation (CIM) is rare. We retrospectively evaluated five patients with CIM and HFS among a series of 103 subjects. The frequency of HFS associated to CIM was of 4.85%. The clinical profile did not differ from the classical primary cases except for young-onset development of facial spasms in patients with CIM. Three patients were treated with BTX-A injections with favorable outcome. Although rare HFS may be associated with CIM especially in young subjects with peculiar phenotypic characteristics (short neck). Moreover, BTX may be an alternative to posterior fossa decompression in selected cases.