ObjectiveHigh resting end-tidal CO2(PetCO2) has been shown to be an independent predictor of systolic blood pressure (SBP) in women, particularly older women. The study reported in this article investigated whether the tendency to experience, express, and/or suppress anger contributes to the association of PetCO2and SBP in women and in men.MethodsThe Spielberger Anger Expression Inventory was administered to 403 healthy male and female participants in the Baltimore Longitudinal Study on Aging. Resting PetCO2was obtained by means of a respiratory gas monitor, and resting blood pressure was obtained with an oscillometric device. The associations of resting PetCO2and the anger scales with SBP and diastolic blood pressure (DBP) were investigated using multivariate regression analyses.ResultsPetCO2, as well as age and body mass index, was an independent predictor of SBP in women with low, but not high, trait anger and in women with low, but not high, anger-out. PetCO2was not an independent predictor of SBP in men with either high or low anger. In addition, PetCO2was not an independent predictor of DBP in either men or women.ConclusionsThe results of this study indicate that inhibition of anger potentiates the relationship of high PetCO2with SBP in women but not men. Additional studies are needed to determine the origins of the observed gender differences and the psychophysiological pathways by which high resting PetCO2contributes to elevated resting blood pressure in women.