INTRODUCTION: The aim of the study was to find out, if there was a differencein function of the blood/cerebrospinal fluid barrier (BCSFB) in females and males, and if those differencesintensify with age. MATERIAL AND METHODS: 120 patients of both sexes who underwent subarachnoideal anesthesiawere divided into 6 groups, 20 patients each, considering sex and age criteria. Samples of venous blood(5 ml) and cerebrospinal fluid (1 ml) were collected from every patient simultaneously; then albuminpermeability indexes (Qalb) were counted. The achieved results were compared using the t-Student testat the significance level of P < or = 0.05. RESULTS: The mean value of Qalb in patients aged 20-50 wassignificantly lower than in the group of patients aged 51-70, as well as in the group of patients over71. The difference between mean Qalb values in patients aged 51-70 and those aged over 71 was also statisticallysignificant. No statistically significant difference between mean Qalb values in females and in malesin the corresponding age groups was found. In every age group the value of albumin permeability indexwas lower in females. CONCLUSIONS: 1) The permeability of BCSFB increases with age. 2) There was no statisticallysignificant difference between the values of albumin permeability index in females and males in the correspondingage groups. The function of BCSFB in the corresponding age groups of males and females was the same.

Keywords: Sex Characteristics