Deoxyribonuclease I gene exhibits polymorphisms, including a single nucleotide polymorphism (A2317G) and a 56 bp variable number of tandem repeat, designated as HumDN1. G2317 was regarded as an independent risk factor for Japanese myocardial infarction (MI) patients. We investigated the association between either A2317G or HumDN1 polymorphism of deoxyribonuclease I gene and MI in Han Chinese population. A2317G and HumDN1 polymorphisms in 278 MI patients and 297 unrelated controls were detected by PCR and PCR-restriction fragment length polymorphism. Plasma lipids were measured in fasting state by biochemical methods. A new HumDN1 genotype -HumDN1 4/6 was found in Han Chinese MI patients. Genotype distributions and allele frequencies of A2317G and HumDN1 did not differ between MI patients and control group (all P > 0.05). In addition, none of estimated haplotypes significantly increased or decreased the risk of MI. In analysis of covariance, plasma total cholesterol was observed to be associated with HumDN1 genotypes in MI patients (P = 0.02). Our data suggest HumDN1 genotypes are related to total cholesterol levels in Han Chinese MI patients, but deoxyribonuclease I gene polymorphisms are not associated with susceptibility to MI in Han Chinese.