One potential approach to individualizing BP treatment decisions is to conduct N-of-1 trials: a multiple crossover design conducted in a single patient. Despite the appeal of this approach, there are few published reports of BP medication N-of-1 trials. Therefore, the objective of this study is to determine the feasibility of conducting an N-of-1 BP medication trial in hypertensive patients. Patients who meet all the eligibility criteria will be asked to monitor their blood pressure and side-effects while taking a series of commonly prescribed blood pressure medications. If they are already taking a blood pressure medication, they will begin by tracking their blood pressure and side-effects while taking this medication for 1 week. They will then be asked to track their blood pressure and side-effects while taking a series of up to three other blood pressure medications (losartan - a renin-angiotensin system blocking agent, amlodipine - a calcium channel blocker, and hydrochlorothiazide - a thiazide diuretic). Each of these medications will be taken for 2 weeks at a time. The specific choice of medications and medication doses will be selected by the study physician. Unless patients have side-effects that lead them to discontinue a medication early, patients will be expected to take each medication at least twice in a balanced sequence (e.g., losartan - amlodipine - HCTZ - HCTZ - amlodipine - losartan). Patients will measure their blood pressure and medication side-effects during the 2nd week on each of these medications. Patients will have the option of escalating or decreasing dosages to identify the single medication/medication dose that best lowers their blood pressure with the least side-effects. Blood pressure will be measured using an Omron home blood pressure monitor. Side-effects will be tracked using a daily e-mailed survey that is completed over the Internet.