This study was aimed at evaluating the toxic effects of a prenatal exposure to lead acetate (Pb) on bone tissue of newborn rats, and potent protective effects of spirulina (Arthrospira platensis) added to diet. Female rats were given a normal diet or a diet enriched with spirulina. Additionally, lead acetate was administered to one half through drinking water from the 5th day of gestation to day 14 post-partum. In the Pb group, a decrease in body and femur weights as well as in femur length of pups was noted. Lipid peroxidation was increased, while superoxide dismutase, catalase and glutathione peroxidase activities in femur were decreased. Our results also showed lead deposition in the blood and femurs of newborns. Moreover, lead caused a significant decrease in calcium and phosphorus levels in bone, yet, in plasma, they increased and decreased inversely. Besides, plasma total tartrate-resistant acid phosphatase was enhanced, while total alkaline phosphatase was reduced. Bone disorders were confirmed by femur histological changes. Conversely, no such damages or biochemical changes were found in neonates from spirulina fed lead-poisoned mothers. These results strongly suggest that beneficial effects of spirulina proceeded through the reduction of the lead-induced oxidative stress and related damages.