The scavenger receptor class B type I gene can protect against atherosclerosis; a mononucleotide polymorphism is associated with differences in blood lipid metabolism, postprandial serum lipid levels, insulin resistance, coronary artery disease and familial hyperlipidemia. In this study, the scavenger receptor class B type I gene exon 1 G4A gene polymorphism in atherosclerotic cerebral infarction patients, cerebral hemorrhage patients and normal controls was detected using the polymerase chain reaction-restriction fragment length polymorphism method. The results showed that the GA + AA genotype frequency of scavenger receptor class B type I gene G4A in atherosclerotic cerebral infarction patients was similar to that in cerebral hemorrhage patients and normal controls; however, the A allele frequency was significantly lower than that in normal controls. The serum level of high-density lipoprotein cholesterol in patients with the scavenger receptor class B type I gene G4A GA + AA genotype was significantly higher, while the serum level of low-density lipoprotein cholesterol was significantly lower than that in patients with the GG genotype, in both the atherosclerotic cerebral infarction and cerebral hemorrhage groups. The serum level of high-density lipoprotein cholesterol in patients with the scavenger receptor class B type I gene G4A GA + AA genotype was significantly higher, while the serum levels of low-density lipoprotein cholesterol and total cholesterol were significantly lower than those in normal controls with the GG genotype. Our experimental results suggest that the G4A polymorphism of the scavenger receptor class B type I gene is a possible predisposing risk factor for atherosclerotic cerebral infarction, and that it has no association with cerebral hemorrhage in the Han population in Hunan province of China. The A allele is possibly associated with the metabolism of high-density and low-density lipoprotein cholesterol. The scavenger receptor class B type I gene can protect against atherosclerosis; a mononucleotide polymorphism is associated with differences in blood lipid metabolism, postprandial serum lipid levels, insulin resistance, coronary artery disease and familial hyperlipidemia. In this study, the scavenger receptor class B type I gene exon 1 G4A gene polymorphism in atherosclerotic cerebral infarction patients, cerebral hemorrhage patients and normal controls was detected using the polymerase chain reaction-restriction fragment length polymorphism method. The results showed that GA + AA genotype frequency of scavenger receptor class B type I gene G4A in atherosclerotic cerebral infarction patients was similar to that in cerebral hemorrhage patients and normal controls; however, the A allele frequency was significantly lower than that in normal controls. The serum level of high-density lipoprotein cholesterol in patients with the scavenger receptor class B type I gene G4A GA + AA genotyp the serum level of low-density lipoprotein cholesterol was significantly lower than that in patients with the GG genotype, in both the atherosclerotic cerebral infarction and cerebral hemorrhage groups. The serum level of high-density lipoprotein cholesterol in patients with the scavenger receptor class B type I gene G4A GA + AA genotype was significantly higher while the serum levels of low-density lipoprotein cholesterol and total cholesterol were significantly lower than those in normal controls with the GG genotype. Our experimental results suggest that the G4A polymorphism of the scavenger receptor class B type I gene is a possible predisposing risk factor for atherosclerotic cerebral infarction, and that it has no association with cerebral hemorrhage in the Han population in Hunan province of China. The A allele is possibly associated with the metabolism of high-density and low-density lipoprotein cholesterol.