Of 26 cases with pheochromocytoma which had been proved on operation,pathological examination was done in 21 cases.The authors analysed the cardiovascular complications in these patients and correlated them with the pathologic findings of the tumor.The results showed that patients with predominantly epinephrinesecreting tumors were prone to post-hypertesive hypotension,arrhythmia with rapid heart rate and catecholamine-induced myocardosis.Some illustrative examples were presented and path-ophysiology of these complications were discussed.