As a common infectious disease in the elderly, gingivitis is caused by microbial plaque on tooth supporting tissues. In order to investigate whether there is a linkage between the gingivitis and hemorheology of elderly patients with lacunar infarction, 123 cases of patients were divided into two groups, i.e. a severe gingivitis group (33 patients with a gingival index ³ 2.1) and a mild gingivitis group (90 patients with a gingival index < 2.1). The hemorheological variables, i.e. whole blood viscosity, plasma viscosity, whole blood reducing viscosity, hematocrit and plasma fibrinogen of these patients were determined. The statistical T-test results showed that the plasma fibrinogen (Fib) (P < 0.01) and whole blood viscosity at middle shear rate (hbM) (P < 0.05) of patients in the severe gingivitis group were significantly higher than that in the mild gingivitis group. This result revealed that there was a linkage between gingivitis and lacunar infarction. In addition, this study implied that gingivitis would increase the occurrence frequency of lacunar infarction in old people, and the hemorheological variables, hbM and Fib, might be potential indicators for early diagnostics of lacunar infarction.