BackgroundMisdiagnosis and delayed diagnosis in progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) are common. Few studies have systematically evaluated the diagnostic process from symptom onset to death in representative cohorts.MethodsAll PSP/CBD cases (n= 28/2) and age-sex matched Parkinson’s disease (PD) cases (n= 30) were identified from a UK prospective incident Parkinsonism cohort. Medical and research records were reviewed to compare median times from first index symptom to key diagnostic milestones and the nature/timing of secondary care referral and review.ResultsIndex symptoms were similar apart from more tremor in PD (p< 0.001) and more impaired balance (p= 0.008) and falls (p= 0.004) in PSP/CBD. PD was diagnosed a median 0.96 years after index symptom. In PSP/CBD the median times from index symptom to identifying parkinsonism and then including PSP/CBD in the differential diagnosis and the final diagnosis were 1.88, 3.41 and 4.03 years, respectively (allp< 0.001). Survival from symptom onset in PSP/CBD and PD was not significantly different (5.98 vs 6.85 years,p= 0.72). More diagnoses (p< 0.001) were considered in PSP/CBD. Prior to diagnosis, PSP/CBD patients had more recurrent emergency attendances (33.3% vs 10.0%,p= 0.01) and were referred to more specialities than PD (median 5 vs 2). Time to any outpatient referral (0.70 vs 0.03 years,p= 0.025) and to specialist movement disorder review (1.96 vs 0.57 years,p= 0.002) was longer in PSP/CBD.ConclusionsThe duration and complexity of the diagnostic journey were greater in PSP/CBD than age-sex matched PD but can be improved. In this older cohort, there was little difference in survival from symptom onset in PSP/CBD and age-sex matched PD.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00415-023-11629-x.