Routine blood pressure measurements are performed on all non-ambulatory patients attending the Accident and Emergency Department, Leicester Royal Infirmary, England. However, the patient's general practitioner is not always informed of the reading, even if it is found to be raised. One of the chief reasons for this omission is the fact that single, elevated blood pressure readings taken in an accident and emergency department are considered to be of doubtful significance. Sixty patients with a single, elevated blood pressure measurement were studied. Fifteen of these patients were found to continue to have an elevated blood pressure measurement when reviewed in a quiet, relaxed environment. Fourteen of these 15 patients are currently being treated for hypertension after independent assessment by their family practitioners. It was concluded that single, elevated blood pressure readings are useful indicators of hypertension in non-ambulatory patients attending accident and emergency departments. It is, therefore, important to inform general practitioners of incidentally raised blood pressure readings.