Progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS) progress relentlessly and lead to a need for care. Caregiving is often burdensome. Little is known about the course of caregiver burden (CB) in PSP and CBS patients. Longitudinal analysis of CB in family members caring for PSP and CBS patients. Single-center longitudinal pilot study in 68 newly diagnosed patients with probable PSP and CBS (52 Richardson’s syndrome; 1 progressive gait freezing of PSP; 15 CBS). Demographic, educational, occupational parameters, family status, motor functions (UPDRSIII, Hoehn and Yahr Score, Tinetti) and neuropsychological performance (CERAD Plus, Frontal Assessment Battery) were assessed, as well as behavioral and neuropsychiatric impairments (Frontal Behavioral Inventory, Neuropsychiatric Inventory), activities of daily living (ADL) and caregiver burden using the Caregiver Strain Index (CSI), in most patients also the Zarit Burden Interview (ZBI). Patients were followed up every 6 months for up to 2 years. Caregivers reported mild to moderate CB at baseline, which increased by 25–30% in 2 years and was significantly greater in PSP than in CBS. Risk for mental health problems increased over time, especially in female caregivers (depression). Important patient-related factors were apathy, aspontaneity, depression, irritability, disorganization, poor judgment, impairment of language, impairments in ADL, a high educational level of the patient and close family relationship. Behavioral symptoms and impaired ADL are the main patient-related factors of CB in PSP and CBS. CB can be severe and needs to be assessed repeatedly from the time of diagnosis to provide comprehensive support.