Objectives: We investigated the effect of human growth hormone (GH) on newborn rat brain superoxide dismutase, glutathione and malondialdehyde (MIDA) levels in hypoxic-ischemic (H-I) newborn rats. Methods: Fourty-eight 7 days old newborn rats were randomized to a healthy (n: 15), H-I (n: 18) and GH administered H-1 (GH-H-1, n: 15) group. Permanent, left common carotid ligation was performed in the H-I groups. In the GH-H-1 group, 50 mg/kg human GH (Norditropin Simplex, Novo Nordisk A/S) was administered subcutaneously just before carotid artery ligation. Two hours after ligation, rats were subjected to 2 h of hypoxemia and then were decapitated. Right and left cerebral hemispheres (CHs) and cerebellum-brain stem (C-BS) were separated. Results: Glutathione levels of each region were not statistically different from each other in and between the groups. Superoxide dismutase levels were higher in C-BSs compared to CHs (for each comparison p < 0.01). CHs and C-BS MDA levels were similar in the control and H-1 groups but MDA levels of both CHs of the GH-H-1 group were significantly higher than the levels of the H-1 group (p = 0.01; p = 0.024, respectively). Left CH MDA level of GH-H-1 group was higher compared to left CH MDA of the control group (p = 0.045) while there was no difference between right CHs. In the GH-H-1 group, left CH MDA level was higher than the C-BS (p = 0.03). MDA levels of the C-BSs did not differ between the groups (p > 0.05). Conclusion: Although we have not evaluated the effect of GH histopathologically, increased lipid peroxidation especially in the H-1 (left) hemisphere of the GH treated rats might suggest that GH treatment may be harmful in H-1 encephalopathy. Copyright (c) 2006 S. Karger AG, Basel.