Abstract 1. 1. Five amphibian species were studied for the effect of hypophysial hormones on their water balance. The species were three anurans, Rana ridibunda, Bufo viridis and Pelohates syriacus, and two urodeles Salamandra salamandra and Triturus vittatus. 2. 2. In the first four species different stages of development were studied, in the newt both the terrestrial and aquatic phases of the adult were examined. 3. 3. The hormones used were oxytocin (OXY), arginine vasotocin (AVT) and prolactin (PL). 4. 4. Oxytocin caused most water retention when compared with the other hormones, especially responding were juveniles of Rana and Bufo, but also the terrestrial phase of the adult newt Triturus. 5. 5. Arginine vasotocin affected mostly juvenile Pelobates. 6. 6. Prolactin caused water retention in juvenile Rana and in the terrestrial phase of Triturus. 7. 7. In general the hormones affected the juvenile stages more than either larvae or adults.