The prevalence of arterial hypertension in primary hyperparathyroidism (PHPT) is higher than in the general population. With the aim of determining the evolution of hypertension associated with PHPT, we analyzed a group of 56 patients followed for a mean of 60 months (range 10-101 months) after successful parathyroidectomy for PHPT. The study group consisted of 16 men and 40 women. The mean age was 49 +/- 12 years (range 18-73 years). None of the patients had renal impairment. Two hypertensive patients died during the follow-up from complications related to their hypertension. Twelve (21.8%) patients were hypertensive before parathyroid surgery (systolic greater than 160 mmHg and/or diastolic greater than 90 mmHg). Pre-operative midregion serum parathyroid hormone concentration was higher in the hypertensive patients than in normotensive patients (2.7 +/- 2.4 vs 0.82 +/- 0.4 mu iEq/l, p = 0.018). Pre-operative creatinine clearance was lower in the hypertensive patients than in normotensive patients (65.4 +/- 27.5 vs 86.7 +/- 26 ml/min, p = 0.002). There were no significant differences between normotensive and hypertensive patients in age, sex, body weight, clinical manifestations, weight of parathyroid tissue removed, and calcium metabolism, or in plasma concentrations of magnesium, uric acid, cholesterol, proteins, or albumin. During follow-up, none of the patients with pre-operative hypertension became normotensive, whereas 32% of the patients who were normotensive preoperatively developed clinical hypertension. The global prevalence of postoperative hypertension was thus 48%. The patients that developed hypertension after parathyroidectomy were followed for a longer period than the normotensive patients (76 +/- 17 vs 53 +/- 10 months, p = 0.005), had a lower postoperative creatinine clearance (74 +/- 28 vs 90 +/- 25 mg/min, p = 0.07), and higher cholesterol levels (6.2 +/- 1.5 vs 5.5 +/- 0.9 mmol/L, p = 0.08).(ABSTRACT TRUNCATED AT 250 WORDS)