It is well known that combinations of risk factors result in higher risk than their mere sum. The present paper describes, in quantitative terms, the differences between risks pertaining to equal blood pressure elevations at different constellations with other risk factors (smoking and hypercholesterolaemia). From the practical point of view, this concept of 'constellation risk' convincingly underscores the need for controlling, in hypertensive patients, coexisting hypercholesterolaemia and smoking. Also, at equal blood pressure elevations, smoking and hypercholesterolaemic patients are in greater need of antihypertensive medication. This applies in particular to the range of mild hypertension, where individual decisions have to be taken whether to initiate drug treatment.