We report 4 patients with young-onset monogenetic parkinsonism, each of whom was misdiagnosed with either a psychogenic movement disorder or chronic fatigue syndrome for 10 to 23 years after the onset of their first symptoms. Once the diagnosis was eventually made, they all had a rapid and excellent response to levodopa, albeit with the early appearance of interdose dyskinesias in 3. We discuss possible reasons for the missed diagnosis despite the relentless progression of their motor handicap. DAT scanning supported the revised clinical diagnosis of parkinsonism. © 2011 Movement Disorder Society.