OBJECTIVE To investigate the relationship between the polymorphism of angiotensin converting enzyme (ACE) gene and ACE inhibitor (ACEI)-induced cough in Chinese elderly with essential hypertension. METHODS ACE I/D polymorphism was performed on DNA samples from patients using the polymerase chain reaction (PCR) followed by agarose gel electrophoresis. Serum ACE levels were measured using a colorimetric assay. RESULTS The frequencies of ACE II genotype were 40% in patients with cough and 20% in those without cough, respectively (P < 0.05). The frequencies of I allele were 60% in patients with cough and 41% in those without cough (P < 0.01); The serum ACE level was highest in the DD genotype, followed by the ID genotype and the II genotype. The ACE level in patients with cough was significantly lower than that in patients without cough (P < 0.001). The sensitivity and specificity were 81% and 78% respectively when the serum ACE levels were used to predict ACEI-induced cough. CONCLUSIONS ACEI-induced cough was related to the serum ACE level and ACE gene polymorphism in Chinese elderly with essential hypertension.