The cardiovascular effects of betel nut were studied in 47 healthy male subjects who were divided into three groups: chronic, occasional and new chewers. Cardiovascular responses measured included heart rate and blood pressure changes following betel chewing. All three groups showed a significant increase in heart rate lasting an average of 16.8 minutes. On the other hand, only the new chewer group showed an increase in systolic blood pressure. Present data indicate that betel chewing can affect cardiovascular function, and that tolerance to the pressor response may occur in habitual users.