Insufficient awareness of hypertension guidelines by physicians may be an impediment to achieving adequate blood pressure (BP) control rates in clinical practice. We therefore conducted an open intervention survey among primary care physicians in 1596 centres from 16 countries in four different continents to prospectively assess what is the BP goal defined by physicians for individual patients and what are the reasons for not intensifying antihypertensive treatment when BP goals are not achieved. Enrolled patients (N=35,302) were either not treated to goal (N=22,887) or previously untreated (N=12,250). Baseline systolic and diastolic BP averaged 159/95+/-15/12 mm Hg. BP goals defined by physicians averaged 136+/-6 mm Hg for systolic and 86+/-5 mm Hg for diastolic BP. Patients' individual risk stratification determined BP goals. At last visit BP averaged 132/81+/-11/8 mm Hg and values of <or=140/90 were reached in 92% of untreated and 80% of previously uncontrolled treated hypertensives. The main reasons for not intensifying antihypertensive treatment when BP remained above goal were the assumption that the time after starting the new drug was too short to attain its full effect, the satisfaction with a clear improvement of BP or with a BP nearing the goal, and the acceptance of good self-measurements. In this open intervention program in primary care, a large proportion of patients achieved recommended BP goals. The belief that a clear improvement in BP is acceptable and that the full drug effect may take up to several weeks to be reached are frequent reasons for treatment inertia when goals are not achieved.