Blood pressure is an inherently variable phenomenon. In addition to this the level rises in the clinical setting; a response which is extremely variable. Problems therefore arise in the diagnosis and treatment of hypertension. Studies have shown that blood pressure can reliably be measured at home either with a stationary or ambulatory apparatus. The readings which are reproducible are generally lower than those obtained in the clinic. Ambulatory recordings are a more reliable guide to prognosis and to the response to hypotensive agents. Home recordings should therefore be more widely used in diagnosis and treatment of the disorder.