Hereditary diffuse leukoencephalopathy with spheroids is a rare genetic disorder caused by mutations of the colony-stimulating factor 1 receptor gene. It is an adult-onset leukodystrophy, with a wide spectrum of neurological and psychiatric manifestations that includes Parkinsonism, dementia, seizures, limb weakness, spasticity and abnormal motor behaviour. Alien-hand syndrome and mirror movements are rare manifestations of this and other neurodegenerative disorders. We describe a woman with progressive limb and trunk rigidity, Parkinsonism and dementia, who also had involuntary left arm levitation (part of the posterior variant of alien-hand syndrome) and left-hand mirror movements. We discuss the different types of alien-hand syndrome, and the likely mechanisms of arm levitation and mirror movements.