The oviducts of Hemidactylus flaviviridis exhibited seasonal changes and their enlargement coincided with a gradual increase in the size of the ovaries. During the breeding season (April) the oviductal wall was lined by tall, columnar epithelium which consisted of flask-like ciliated and nonciliated cells. The epithelium reacted strongly with PAS and Sudan Black-B and exhibited delta 5-3 beta-hydroxysteroid dehydrogenase (delta 5-3 beta-HSD) and Glucose-6-phosphate dehydrogenase (G-6-PD) activity indicating that the oviducts of this lizard might be involved in the steroid metabolism. In the nonbreeding lizards the oviduct showed degeneration marked by the reduction in the size and height of the epithelium which contained Sudan Black-B but not PAS positive granules. It also lacked delta 5-3 beta-HSD and G-6-PD activity. Ovariectomy resulted in decreased activity of the oviduct. When the specimens having small, previtellogenic ovarian follicles and regressed oviduct were treated with FSH alone or with a combination of FSH and LH, the epithelium of the oviduct showed stimulatory changes as indicated by the increased epithelial cell height and high delta 5-3 beta-HSD and G-6-PD activity. By contrast, LH alone remained without marked effects.