Gentamicin was evaluated for developmental toxicity in pregnant Sprague-Dawley rat. Gentamicin was administered subcutaneously on days 6-15 gestation at dose of 100 mg/kg. On gestation day 21, all live fetuses were examined for external and skeletal malformations and variations. Increased resorptions and dead fetuses, and reduced fetal body weight were observed at dose of 100 mg/kg. Gentamicin caused severe skeletal anomalies, such as: wavy ribs, incomplete ossification of sternebrae, tail vertebra, metacarpus, metatarsus and calvaria. These results indicate the nature and extent of embryotoxicity and teratogenicity of gentamicin in Sprague-Dawley rats.