The present study analyzes the influence of the Type A personality trait, called hostility, on the development of primary arterial hypertension. Recent studies show incongruent results regarding the interrelation of these two constructs; therefore, this research is mainly oriented to clarify these antecedents by means of a measurement instrument constructed from the items used in the Minnesota Multiphasic Personality Inventory. This instrument seeks to obtain a profile of the subject's hostility trait along with a clinical and sociodemographic profile. By comparing the results of patients with arterial hypertension or diabetes and subjects who are unaware of their health status in relation to this condition, the relationships between each of the components of the personality trait, the symptoms pertaining to this disease and the condition itself are analyzed, thus providing an explanation that clarifies some of the doubts concerning this psychological phenomenon.