Compliance with antihypertensive therapy was measured before and after distribution of non-automatic blood pressure devices. After 2 weeks of placebo treatment, 37 patients were treated with an antihypertensive combination drug containing triamterene. Adherence to therapy was assessed over 8 months by measuring urine fluorescence due to triamterene at intervals of 2-4 weeks, unknown to the patients. After 3 months of therapy, all patients, not just those with poor compliance, were given blood pressure devices and were carefully instructed in their use. The results showed that self-recording of blood pressure increased the compliance rate in the total group from 65% at the beginning of the study to 81% at the end. In those who initially showed poor compliance, there was an increase in compliance from 0 to 70% after self-measuring of blood pressure was introduced. We conclude that self-recording of blood pressure may be of value in patients with unsatisfactory blood pressure responses in whom poor compliance is suspected.