This study evaluated the relationship between baroreceptor reflex sensitivity and cognitive performance. Twenty normal subjects performed the Uchida-Kracpelin test, a serial arithmetic task. Baroreceptor reflex sensitivity during a 5-min Uchida-Kraepetin test was assessed in minute periods by spectral analysis using the maximum-entropy method. During the task, baroreceptor reflex sensitivity was significantly reduced. There was an inverse between -subjects association between baroreceptor reflex sensitivity and the level of performance (number of additions completed) both at different time periods of the Uchida-Kraepelin test and during the whole task (r = -.51). This finding supports the existence of a pathway mediating Mutual cardiovascular-central nervous System influences through the baroreceptors, establishing an essential mechanism facilitating adaptive reactions to stressful conditions.