Persistent mirror movements (MM) are involuntary movements executed on one side of the body during voluntary movements of the contralateral homologous body parts which may abnormally persist into adulthood. Brain electric source analysis (BESA) was used to compare the sources of movement-related cortical potentials from a group of subjects affected by persistent mirror movements with those of a control group. We studied two possible dipole models: a) Bilateral sources in both primary motor cortices; b) sources in both motor cortices together with a midline source in the region of SMA.Results: Model a): During unilateral movements normal subjects showed a clear preponderance of the dipole source contralateral to the movement. Whereas in subjects with MM we found fairly symmetric dipole sources in both motor cortices.Model b): Normal subjects demonstrated no relevant activity of the source in between the hemispheres. In the MM group however, we found an large activity of this midline source.Conclusion: We assume that subjects with MM have an abnormal activation of both primary motor areas and an additional activation of mesial motor structures (SMA or cingulate motor areas).