Organized teetotalers were examined with regard to gamma-glutamyl transferase (GGT) in the serum. The mean values for GGT in the group of teetotalers (0.32 mukat/l +/- 0.23) was considerably lower compared with a group of the general population (0.50 mukat/l +/- 0.48), p less than 0.001. Only a few teetotalers had GGT values more than 1.0 mukat/l. A certain tendency to higher values was found among middle-aged men compared to women. No statistically significant correlation between GGT and age was found.