Among the enzymes that are of clinical interest in liver disease is the gamma glutamyl transferase (GGT) levels which plays a key role in the metabolism of glutathione and amino acid transport. To study their statistical distribution, variations by age and sex and establish reference intervals in apparently healthy population of Villa Clara were formed three study groups comprised 45 newborns, 40 children and 60 adults. In each case the percentage of male and female was approximately 50%. GGT activity was determined by a kinetic method from serum in a clinical chemistry analyzer Hitachi with Helfa Cuban reagents. Only significant differences in gender in the adult group so that infants and children were taken as unique groups, regardless of gender. In each age group was determined statistical distribution and established reference values for GGT, taking the central interval (90%) defined by the 5th and 95th percentiles. The result was that the GGT in cord blood provides a broad range of activity with a mean value significantly higher than children and adults. In school-age infants serum enzyme, although smaller, are similar to those of adults, mostly female group. The enzymatic activity is significantly greater men than in women. With this work we comply with the principle that each parameter must be studied in particular populations of clinical laboratory users, as they are dependent on many factors.