With the purpose of studying the relationship between type A behaviour pattern (TABP) and cardiovascular reactivity in the natural work environment, the presence of type A, heart rate (HR) and systolic and diastolic blood pressure (SBP, DBP) during two cognitive tasks were evaluated in a group of business managers (46 men and six women) of a large organization. Habits associated with cardiovascular risk (sedentarism, smoking, alcohol consumption and obesity) as well as other biological risk factors (familiar and personal history of cardiovascular problems, cholesterol and triglyceride level) were also assessed. On results showed that when solving cognitive tasks--abstract reasoning (AR) and mental arithmetic (MA)--within the work environment, these stimuli produced a significant reactivity in heart rate, SBP and DBP and also in a subjective measure of stress. The majority of participants reached peak values of HR and SBP during the MA task, whereas DBP was mostly activated during the AR task. SBP was significantly higher at the beginning of the experimental session than during the resting periods or between tasks, and HR at the beginning of the session, was associated with the level of performance. Type A's and B's differed in their SBP taken just before leaving the session. These results indicate the importance of taking into account, aside from the resting measures, the entering and leaving periods of an experimental session. A very high proportion of the subjects studied were classified on type A behaviour (85%). Sedentarism, alcohol consumption and family history were also more frequent in this group. A very high proportion of participants had more than two biological risk factors or habits associated with cardiovascular risk. A's and B's were significantly different in personal history and hypertension, being A's at higher risk. The reduced number of type B's in this group did not allow further conclusions.