Pheochromocytoma and paraganglioma are rare causes of endocrine hypertension. These are adrenal or extra-adrenal tumors that secrete catecholamines and often cause episodic hypertension. Clinical suspicion should lead to biochemical testing and if confirmed, imaging studies should be performed. The most typical symptoms at presentation besides paroxysmal hypertension include headaches, tachycardia, and sweating. In familial syndromes associated with pheochromocytoma, the condition may be diagnosed during screening tests and of these patients may not have hypertension at diagnosis. Incidentally detected adrenal masses while performing abdominal imaging might result in the diagnosis of pheochromocytomas. Treatment is surgical, but careful preoperative preparation and close postoperative monitoring is needed. This chapter will focus on pheochromocytoma/paraganglioma syndromes. Other causes of endocrine hypertension that occur in severe cases of hyperthyroidism, Cushing syndrome, apparent mineralocorticoid excess syndrome, and acromegaly are reviewed elsewhere.