Abstract 1. 1. Lizards with different preferred temperatures were water-loaded, and their ability to excrete excess water and conserve electrolytes was tested at several temperatures. 2. 2. Rates of water excretion were much less temperature dependent in lizards having a low preferred temperature, but were maximal at about 30–35°C in both species. 3. 3. Urinary sodium levels were minimal at temperatures near the respective preferred temperature of each species. 4. 4. Urinary potassium levels were low and apparently not temperature dependent over most of the range studied, but increased as lethal temperatures were approached.