Sudden hypertensive surges are often observed in patients with primary hypertension. Even though the possibility of a pheochromocytoma almost automatically comes to mind, this diagnosis is confirmed only in a few patients (less than 1%). The case of a 55 yr old patient with very high posture-or emotion-induced hypertensive paroxysms, often associated with chest pain and flushing is described. All laboratory tests were normal except for plasma catecholamines, which were high especially during stress tests (Tab. II). The existence of a pheochromocytoma was excluded on the basis of repeatedly normal urinary catecholamine levels after hypertensive crises and a negative CT abdominal scan and I131 MIBG adrenal scintigraphy. An alteration of the baroreceptor reflex was ruled out, as the blood pressure response to autonomic function tests was normal. The cause of the orthostatic hypertensive crises could not be attributed to hypovolemia, as plasma volume proved normal. Measurement of circulating catecholamines showed elevated free plasma epinephrine with low conjugated epinephrine indicating a defective conjugation of this amine. This finding suggests an injured inactivation of epinephrine and might be involved in the pathogenesis of the hypertensive crises observed. Continuous intra-arterial blood pressure monitoring demonstrated the existence of mild hypertension with a normal 24-hour blood pressure pattern. However, the tracings were interspersed with numerous blood pressure peaks. Average 24 hour blood pressure was normalized by the therapy, but the hypertensive crises were not controlled by any of the drugs used. The absence of target organ damage despite the spectacular rises in blood pressure suggests that the cardiovascular system is well able to withstand hypertensive episodes if they are short lived.