1. The pressure thresholds at which the aortic baroreceptors cease firing and attain continuous firing were determined in rats with renal hypertension of up to 2 months' duration.
2. After control recording the kidney was undipped and, if necessary, the rats were bled to restore normal pressure. After 1 and 6 h the baroreceptors were again studied.
3. It was found that the entire baroreceptor pressure range shifted progressively downward to normal levels after the normalization of pressure.