OBJECTIVE: To identify the relationship between angiotensin-converting enzyme (ACE) gene polymorphism and heart rate variability in cerebral stroke patients. METHODS: An insertion/deletion(I/D) polymorphism of the ACE gene was analyzed by polymerase chain reaction in 43 normal subjects, 46 patients with ischemic cerebral stroke, and 40 patients with brain hemorrhage; their heart rate variability(HRV) parameters such as time domain and power spectral component were analyzed. RESULTS: The frequency of DD genotype and the frequency of deletion alleles in cerebral stroke groups were significantly higher than those in control groups (P<0.01), and the measured components of HRV, including total power (TP), low frequency power (LF), high frequency power (HF), LF/HF, and choas, were higher in the patients with the ACE DD genotype when compared with those in the patients with the ACE II, ID genotypes; there was significant difference in effective rate (P<0.05). CONCLUSION: The above related parameters of HRV were correlated with heritability, suggesting that the cerebral stroke patients with the ACE DD genotype are at high risk of cerebrogenic cardiac autonomic nerve function disturbances.