Metabolic bone disease (MBD) is a pathologic demineralization of the skeleton occurring in numerous species due to various factors. MBD affects a great number of captive green iguanas (Iguana iguana), most cases are the result of failure of the owner to provide a proper diet and environment. Typically the failure to provide adequate husbandry results in a condition in which a juvenile green iguana experiences skeletal demineralization and develops skeletal deformities. A less common presentation of MBD that is occurring with greater frequency is a condition in which the adult green iguana develops renal dysfunction that leads to loss of calcium homeostasis that results in muscle tetany and skeletal demineralization. Two cases presented to Cornell University's Hospital for Animals exotic animal clinic are discussed that exemplify different presentations, diagnoses, pathophysiology and treatments of MBD in the green iguana.