Hypertension is a long-term medical condition in which the pressure of blood travelling through the arteries is too high. This puts increased strain on the heart which, if left untreated, can lead to increased risk of heart attack or stroke. It is extremely common and is a major cause of death and disease worldwide, however many cases remain undiagnosed and treatment is not as effective as it could be. General practitioners play an important role in the early diagnosis and treatment of high blood pressure. In general, patients are treated with a combination of different drugs, as using a single drug is only effective in a limited number of patients. If initial treatment with two drugs fails then the current guidelines recommend increasing the dosage of these drugs, switching to two different drugs or adding a third drug. If treatment with three drugs is needed, the guidelines favour the use of fixed-dose or single-pill combinations, because reducing multiple drug treatment to one tablet daily helps improve the chance of patients always remembering to take their medication. The aim of this study is to complete a large-scale survey to investigate how well blood pressure is controlled in hypertensive patients who are being treated with more than one blood pressure medication.