Glutathione S-transferase (GST) has been quantified and characterized in healthy human anagen hair follicles obtained from 36 men and 36 women (26 +/- 7 years of age). GST activity was determined using 1-chloro-2,4-dinitrobenzene as a substrate, and the values in men were: 0.5 +/- 0.2 mU/follicle, significantly different from women (0.36 +/- 0.2 mU/follicle); 196 +/- 98 mU/mg protein and 309 +/- 158 mU/mg DNA without significant differences from women. Enzyme activity showed a high degree of inter-individual variability (23.5-fold when expressed per follicle, 18.29-fold expressed per mg of protein and 22.75-fold per mg of DNA) in the whole population and this variability was higher in women. Ion-exchange chromatography by KCl and enzyme immunoassay suggest that the GST present in hair follicles corresponds with the acidic form. The percentage of anagen hairs in each subject showed a positive correlation with the following parameters: GST/hair, GST/DNA and DNA/hair. It is concluded that GST may contribute to the maintenance of the hair growth cycle.