Some experiments on uremia in rats may require an overnight fast in order to empty the gastrointestinal tract, or for other reasons. Previous investigation of normal rats showed that an overnight fast is not completely innocuous and that feeding pure sucrose is a valuable alternative. In the present study, anephric uremic rats were fasted or fed sucrose for 20 h. Sucrose feeding resulted in lower serum urea values and less loss of liver weight. Therefore, feeding sucrose overnight is preferable to starvation in uremic rats, as in normal rats.