The cerebrospinal fluid (CSF)/serum albumin ratio has been used a marker for blood CSF barrier permeability in 116 normal patients. We attempted to correlate the CSF/serum albumin ratio with a number of clinically measurable parameters including alcohol consumption. Alcohol consumption had a significant effect on the blood-CSF barrier. Our data indicate that alcohol increases blood CSF barrier permeability in a dose-dependent manner. The measured values of parameters indirectly indicative of alcohol consumption, such as gamma-glutamyltranspeptidase (gamma-GT) and erythrocyte mean corpuscular volume (MCV), were also correlated with enhanced blood-CSF barrier permeability. Although an apparent influence of age, body weight and sex on blood-CSF barrier permeability was observed, these correlations were not separable from the effect of alcohol consumption.