Cord blood has numerous facilities for life and used in many different areas. Cord blood contains many different catalytic proteins including antioxidant enzymes. Here we purified human cord blood glutathione reductase (hcbGR), glutathione S-transferase (hcbGST) and human cord blood glutathione peroxidase (hcbGPx) from human cord blood erythrocytes and analyzed the inhibition effects of the antibiotics incorporating cefuroxime, ceftriaxone, ceftizoxime and cefoperazone, on these enzymes. K-I values for the drugs ranged from 10.42 to 28.72 mu M for hcbGR, 32.7 to 244.8 mu M for hcbGPx, and 32.39 to 267.3 mu M for hcbGST. Cefuroxime caused the highest inhibition on all enzymes with K-I values of 10.42, 32.39, 32.7 mu M for hcbGR, hcbGST, and hcbGPx, respectively. All drugs displayed non-competitive inhibition regardless of their structures. Since these drugs are often used during pregnancy, identification of possible undesired impacts on various parameters has a great importance for pharmacological and medical applications.