The function of the arterial baroreflex has traditionally been assessed by the measurement of reflex changes in heart rate or sympathetic nerve activity resulting from experimenter-induced manipulation of arterial blood pressure (Oxford method, also termed pharmacological method). However, logistical and flexibility limitations of this technique have promoted the development of new methods for assessing baroreflex function, such as the evaluation of changes in spontaneous arterial pressure and heart rate. While this new spontaneous method has been validated in dogs and humans, it has not been rigorously tested in rats. In the current study, the method of correlating spontaneous changes in systolic blood pressure and heart rate was evaluated in resting, normotensive Sprague-Dawley rats. This technique was found to be neither reliable nor valid under the conditions employed in the present protocol. We also tested a variation of the spontaneous method, which evaluates particular sequences of data during which arterial pressure and pulse interval are changing in the same direction for at least three consecutive heartbeats (sequence method). The sequence method did not provide extra reliability or validity over the spontaneous method. We conclude that, due to the restricted range of variability obtained by measuring spontaneous blood pressure fluctuations, the spontaneous and sequence techniques do not provide data that are comparable to the traditional method of assessing heart rate changes triggered by arterial blood pressure increases and decreases induced by vasoactive drugs. However, it is possible that surgical stress obscured the relationship between blood pressure and heart rate, and therefore further studies are needed to determine whether the spontaneous and sequence methods can be applied to rats during different behavioral states.