The object of this work was to search the effects of hyperoxia and preventive effect of gelsolin on neonatal rat kidneys by analyzing activities of antioxidant enzymes, MDA levels, DNA damage and light microscope examination. Animals were grouped into four (10 animals in each) where the first was served as a control, second was served as a hyperoxic control group (>= 85% O-2), whereas the remaining gelsolin groups were treated with gelsolin (10 ng/kg bw/day gelsolin), and a combination of gelsolin and hyperoxia for 7 days. Changes in malondialdehide levels, activities of antioxidant enzymes, tail DNA%, and tail length indicating DNA damage and histopathology of kidney were evaluated. Hyperoxia increased the level of MDA and decreased enzyme activities compared with control significantly. Tail DNA%, tail length and moment statistically changed in hyperoxia treated groups when compared to gelsolin and control groups. Atrophy, glomerular lobulation, hemorrhage and tubular degeneration were detected as histopathological changes in pups' kidney under hyperoxic condition. Gelsolin caused increases in all anti-oxidant enzyme activities and decreases in MDA contents. As for the pathological and DNA structure studies, hyperoxia treatment group have proven changes. Gelsolin supplementation was protective against hyperoxia caused histopathological changes. But it was not protect completely.