In a reasonably large proportion of patients who take antihypertensive drugs (10-30%), hypertension appears to be therapy resistant; even the use of three antihypertensives does not lower the blood pressure sufficiently. The average nocturnal blood pressure is a better predictor of cardiovascular events than blood pressure measured during the day. Antihypertensives have a stronger effect on nocturnal blood pressure when taken in the evening rather than in the morning. The exact mechanism of this has not yet been unravelled, but randomised, non-blinded studies suggest that this so-called chronotherapy does indeed lower cardiovascular risk in certain groups. The authors regard this as a promising strategy for patients with therapy-resistant hypertension in whom a nocturnal blood pressure dip does not occur.