In this study, the main antioxidant enzymes (AOE) of glutathione peroxidase (GPX), superoxide dismutase (SOD), catalase (CAT) and myeloperoxidase (MPO) were identified, and the influence of sex and age in healthy human polymorphonuclear leukocytes (PMNL) was determined. The SOD, GPX, CAT and MPO activities were investigated in intestinal parasite negative human PMNL from 109 healthy subjects aged from 6 to 70 years (55 males and 54 females) using simple and sensitive enzyme assays. Blood cells, such as eosinophils, platelets, neutrophils, monocytes, and macrophages also synthesize antioxidant enzymes (ACE). They constitute an important proportion and are also the major participants in a number of pathological conditions that suggest the involvement of AOE. A linear effect of age on SOD activity (p<0.05) both in males and females was found. A similar effect with GPX activity (p<0.05) was observed in males only. This showed that the activities of all these enzymes increase with age. In addition, SOD activity was significantly higher in females than males between the age of 19 and 70 years (p<0.001). This analysis also showed that there is a negative correlation between the CAT-GPX (p<0.05) activities and positive correlations between MPO-GPX (p<0.05) activities only in females. No correlation among the other enzyme activities was found in either sex group. This study showed the activities of antioxidant enzyme activities and the correlations of these enyzmes activities with each other in healthy human PMNLs were age- and sex-dependent. This information may assisit in understanding the importance of antioxidant enzymes in the physiological and pathological conditions associated with PMNL.