Background: Rehabilitation is effective for preventing progression of Parkinson's disease (PD) and parkinsonism, but access to services during the COVID-19 pandemic was difficult. The Japanese already practice high levels of social distancing and personal restraint and are keenly aware of dangers related to infectious disease. We therefore presume that many patients discontinued rehabilitation due to behavioral restraint. Objectives: We investigated whether PD patients and parkinsonism patients attending outpatient rehabilitation facilities in Japan initiated rehabilitation interruptions and their associated reasons before and during the COVID-19 pandemic. Methods: Subjects were PD and parkinsonism patients attending a neurology clinic outpatient rehabilitation department in Japan before and during the first year of the COVID-19 pandemic (February 1, 2019, to January 31, 2021). Patients lost to follow-up were investigated as to how long they attended rehabilitation until interruption. We classified factors causing rehabilitation interruption into COVID-19-related factors, disease factors and social reasons. Results: Among 259 subjects (125 men, 134 women, mean age: 76.6 ± 8.5 years), 133 patients (51.4%) initiated interruption of rehabilitation therapy. Cumulative incidence of interruption events was significantly higher during than before the COVID-19 pandemic (p < 0.001). COVID-19-related factors dramatically increased as a reason for interruption after the pandemic started, but diseaserelated and social factors gradually increased thereafter. Incidences of disease-related and social factors before and during the COVID-19 pandemic How to cite this paper: