Résumé : In a group of middle-aged men exhibiting the type A or B behavior pattern described by Rosenman and Friedman, the excretion of urinary catecholamines and their metabolites has been studied during a working-day period. Simultaneously, heart rate and heart rhythm were analyzed using continuous ECG recordings. No significant differences were observed between subjects classified as type A and those classified as type B, neither in the excretion of catecholamines, in their heart rate profile, nor in the prevalence of arrhythmias. These observations are discussed and compared with data from the literature. © 1979.