Growing evidence suggests that the angiotensin-converting enzyme (ACE) and endothelial nitric oxide synthase (eNOS) genes are associated with risk in a wide range of cancers. The objective of this study was to examine whether two DNA polymorphisms at the ACE insertion/deletion (I/D) and the variable number of tandem repeats in NOS intron 4 (4a/4b) were linked to the risk of developing hepatocellular carcinoma (HCC) in a Chinese population. The polymorphisms at ACE I/D and eNOS 4a/4b were genotyped in 293 HCC patients and 384 healthy control subjects using polymerase chain reaction. The frequencies of the D allele (p=0.003, OR=0.72, 95% CI=0.58-0.90) in the ACE gene of HCC patients were significantly different from the healthy controls, and a significantly decreased HCC risk was associated with the DD genotype in both the recessive (p<0.001, OR=0.19, 95% CI=0.11-0.34) and codominant models (p<0.001, OR=0.26, 95% CI=0.14-0.48). This study provided evidence that the ACE I/D polymorphism is associated with HCC, indicating that the ACE I/D polymorphism contributes to HCC progression in the Chinese population.