: No consensus has been reached on how to define cerebrospinal fluid HIV-1 escape (CSF-E). We describe its prevalence in 1095 paired CSF-plasma HIV-RNA measurements from antiretroviral-treated patients according to several definitions and neurological affections. CSF-E prevalence varied substantially (9.0-38.9%) and was higher in patients with cerebrovascular disorders, HIV-associated dementia and white matter abnormalities. Considering the variability in HIV-RNA quantification assays, the biological relevance of viral escape at different thresholds needs to be accurately assessed.