Objectives: Atherosclerosis is an important cause of stroke and remains a challenge for stroke prevention. Risk factors involved in atherosclerotic stroke and anterior and posterior circulation strokes (ACS and PCS, respectively) are different. The purpose of this study is to investigate differences in risk factors between intracranial and extracranial atherosclerosis (ICAS and ECAS), ACS and PCS, and ICAS/ECAS with ACS/PCS in a Chinese acute ischaemic stroke population. Methods: We analysed 551 ischaemic stroke patients who had been enrolled between August 2005 and July 2008. First, risk factors were compared between non-atherosclerosis, ICAS, ECAS, and combined ICAS and ECAS groups. ICAS and ECAS were assessed with transcranial Doppler and carotid colour Doppler ultrasound, respectively. Second, risk factors were compared between ACS and PCS groups. Stroke lesion was assessed with magnetic resonance imaging. Third, risk factors were compared in ICAS/ECAS associated with ACS/PCS. Results: The risk factor for ICAS was high diastolic blood pressure (OR, 1.075; 95% CI, 1.016-1.138; p=0.013), and the risk factors for ECAS were age (OR, 1.113; 95% CI, 1.046-1.183; p=0.001) and low density lipoprotein (OR, 1.450; 95% CI, 1.087-1.935; p=0.012). Hypertension (OR, 1.090; 95% CI, 1.001-1.109; p=0.027) was associated with PCS. Age (OR, 1.026; 95% CI, 1.011-1.128; p=0.003), male gender (OR, 2.278; 95% CI, 1.481-3.258; p=0.003) and age (OR, 1.067; 95% CI, 1.013-1.123; p=0.014), scores of NIHSS (OR, 1.069; 95% CI, 1.012-1.130; p=0.018) were risk factors for ICAS and ECAS with ACS, respectively. Conclusion: Risk factors are different between ICAS and ECAS, ACS and PCS, and ICAS/ECAS with ACS/PCS. Thus, targeted strategies are needed to consider these differences to prevent, treat and manage these diseases.