Cerebrospinal fluid (CSF) biomarkers (protein tau, phosphorylated tau and amyloid Beta 1-42) are recognized as a supportive feature in diagnosis of Alzheimer's disease (AD) and their role in identifying atypical variants of AD is currently under investigation. We dosed these proteins in nine patients clinically and instrumentally affected by posterior cortical atrophy (PCA), a rare disorder characterized by a progressive neurodegenerative process that involves primarily the posterior brain regions. We compared the obtained values with a large group of AD patients (N = 117), recruited in our neurological department. Our data revealed no differences in the CSF profile between PCA and AD, showing abnormal values of protein tau, phosphorylated tau and amyloid Beta 1-42 in both groups of patients. This study underlines the diagnostic importance of CSF biomarkers in PCA patients, supporting the hypothesis that PCA is an atypical variant of AD with an onset before the age of 65.