Excess weight gain is a major cause of increased blood pressure in most patients with essential hypertension, and also greatly increases the risk for renal disease. Obesity raises blood pressure by increasing renal tubular reabsorption, impairing pressure natriuresis, causing volume expansion due to activation of the sympathetic nervous system and renin-angiotensin system, and by physical compression of the kidneys, especially when visceral obesity is present. The mechanisms of sympathetic nervous system activation in obesity may be due, in part, to hyperleptinemia that stimulates the hypothalamic pro-opiomelanocortin pathway. With prolonged obesity, there may be a gradual loss of nephron function that worsens with time and exacerbates hypertension. Weight reduction is an essential first step in the management of obesity hypertension and renal disease. Special considerations for the obese patient, in addition to adequately controlling the blood pressure, include correction of the metabolic abnormalities and protection of the kidneys from further injury.