The subfornical organ (SFO) is one of the brain circumventricular organs, which is known to mediate some of the central effects of angiotensin II related to sodium and water homeostasis. Since angiotensin II levels are altered with changes in chronic dietary salt intake, we reasoned that the actions of angiotensin II at the SFO might be involved in the regulation of arterial pressure during long-term alterations in dietary salt. The present study was designed to test the hypothesis that long-term control of arterial pressure during chronic changes in dietary salt intake requires an intact SFO. Male Sprague-Dawley rats were randomly selected for electrolytic lesion SFOx (n = 8) or SHAM (n = 9) operation of the SFO. Following a one week recovery period, rats were instrumented with radio-telemetric blood pressure transducers for the continuous 24 hour measurement of mean arterial pressure (MAP) and heart rate (HR), and then were placed individually in metabolic cages. Following another week of recovery, rats were subjected to a 49 day protocol in the following manner: 1) 7 day control period (1.0% NaCl diet); 2) 14 day period of high salt diet (4.0% NaCl); 3) 7 day period (1.0% NaCl diet); 4) 14 day period of low salt diet (0.1% NaCl); 5) 7 day recovery period (1.0% NaCl diet). There were no significant differences in MAP or HR between SFOx and SHAM rats throughout the protocol. These results do not support the hypothesis that the SFO is necessary for regulation of arterial pressure during chronic changes in dietary salt. However, SFOx rats demonstrated significantly less cumulative sodium balance when compared to SHAM rats on days 2-6 of the high salt diet period. These data do suggest the SFO is important in the regulation of sodium homeostasis during chronic changes in salt intake.