Primary aldosteronism (PA) is widely believed to be a relatively benign form of hypertension associated with a low incidence of vascular complications. However, several recent studies showed that cardiovascular complications were not rare in PA. PA is known as one of the most typical forms of sodium-sensitive hypertension. Recently, we found that the sodium sensitivity of blood pressure was a marker for greater risk for cardiovascular complications, especially stroke, in patients with essential hypertension. Therefore, we investigated cardiovascular complications in 58 patients with PA confirmed to be Conn's adenoma. Cardiovascular complications were found in 34% of 58 patients. Coronary artery disease was found in only one patient (1.7%), as angina pectoris. Stroke was found in nine patients (15.5%), four patients (6.9%) with cerebral infarctions and five patients (8.6%) with cerebral hemorrhages. Proteinuria and renal insufficiency were found in 14 (24.1%) and 4 (6.9%) patients, respectively. The incidence of cerebral infarction and renal insufficiency was greater in men than women. The prevalence of proteinuria was greater in patients with than without stroke (P = 0.03) among those aged older than 40 years. These results indicated that cardiovascular complications, especially stroke and proteinuria, were common in patients with PA, and proteinuria might be an indicator for stroke as target-organ damage.