The role of Spirulina (Arthrospira) in preventing cadmium (Cd) teratogenicity in ICR mice was studied. Cd was administered intraperitoneally to female mice at 1.5 mg/kg on gestation day (GD)-7, and Spirulina was given by peroral (intragastric) administration at 62.5, 125, 250, or 500 mg/kg from GD-0 through GD-17 (the day when animals were sacrificed). Because among the mechanisms suggested to account for reproductive damage are oxidative stress and lipoperoxidation, embryonic hydroperoxides were also determined. Treatment with Spirulina at the three highest doses significantly decreased the frequency of fetuses with exencephaly, micrognathia, and skeletal abnormalities induced by Cd. Furthermore, Spirulina treatment significantly and dose-dependently decreased lipid peroxidation, which was dramatically increased by administration of the metal. The results of the present study clearly point to the therapeutic potential of Spirulina in Cd-induced teratogenicity and probably through its antioxidant activity.