Background: Corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP) are neurodegenerative tauopathies. Sporadic and familial cases of PSP and CBD have been noted, but both have not been reported in a single family. Objective: To describe the clinical, oculomotor, balance, functional imaging, histopathologic, and genetic studies in a family with CBD and PSP. Design: A report of the clinical and pathological features in a familial tauopathy. Setting: University of Minnesota. Patients: We evaluated 2 siblings and clinically assessed 20 additional family members. Main Outcome Measures: Demonstration of salient features in deceased and living family members. Results: Histopathologically confirmed CBD in one sibling and PSP in another deceased sibling were demonstrated; both had clinical features of corticobasal syndrome. In addition, 3 siblings had probable PSP by clinical criteria. Genetic studies of 4 affected family members demonstrated the H1/H1 haplotype but did not reveal pathogenic tau mutations. The family history revealed consanguinity. Conclusions: This is the first report, to our knowledge, of CBD and PSP in 2 individuals in a single family who presented with corticobasal syndrome and had other affected siblings with clinical PSP. Despite clinical and pathologic heterogeneity, a unifying genetic etiology appears likely in this familial tauopathy.