In order to further investigate the variations of the ratio of free to total sterols in different categories of olive oil and to test the possibility to use this ratio as a parameter for olive oil quality evaluation, a direct GLC quali-quantitative determination of either free or total sterols was made, and their ratio calculated, over a set 13 samples of extra Virgin oils and over a set of 28 current virgin and lampante oils. In order to study the effects of neutralization on free and total sterols, their amounts and ratio were also determined after the neutralization of the current virgin and lampante oils. The single components of free and total sterols were also analyzed, especially the most represented ones.