Comparative studies on the chemistry and behavioral significance of femoral gland secretions in desert iguanas (Dipsosaurus dorsalis) and green iguanas (Iguana iguana) are reviewed. Field and laboratory studies suggest that femoral gland secretions function in conspecific recognition and range marking. In desert iguanas, secretions are of low volatility and may be detected initially using long-range ultraviolet visual cues. In contrast, green iguana secretions contain a diversity of volatile lipids and appear to be localized by chemoreception. Interspecific differences in femoral gland chemistry may reflect adaptations to the diverse climatic conditions of arid desert and tropical forest environments.