Objective: To study the relationship between the streptococcus sanguis group (SSG) and coronary heart disease (CHD). Methods: A test group of 41 individual diagnosed with CHD were chosen; 18 healthy individuals served as controls. All had undergone coronary angiography. Their social class (including education level and wages earned), their smoking and drinking habits, and their blood lipids and standard of oral health were all recorded. SSG in saliva and subgingival plaque were cultivated in NAYS-B agar plates and counted. SSG were identified into species by routine biochemical reaction and AP-PCR. Results: In multiple-step regression analysis, the amount of SSG in saliva and subgingival plaque were associated with severe coronary atheromatosis after adjusting to the classical risk factors of CHD. The average amount of SSG in saliva was (435 ± 422) x 10⁸ CFU/L in the CHD group and (358 ± 540) x 10⁸ CFU/L in the control group (F = 2.72, P = 0.08); the average amount of SSG from the incisors was (331 ± 484) x 10⁷ CFU/L in the CHD group and (98 ± 164) x 10⁷ CFU/L in the control group (F = 5.54, P = 0.02); the average amount of SSG from the molars was (352 ± 381) x 10⁷ CFU/L in the CHD group and (185 ± 232) x 10⁷ CFU/L in the control group (F = 2.86, P = 0.10). S. sanguis and S. gordonii were more prevalent in the CHD group than in the control group (P < 0.05), whereas S. mitis and S. oralis were the same in both groups (P > 0.05). Conclusion: The increase of SSG in oral floras may play an important role in the occurrence of CHD.