Ultrasound blood imaging can be used to the clinical applications including the in-vivo measurement of erythrocyte aggregation (EA). In the present paper, the ultrasound blood images were measured at both radial (RA) and common carotid artery (CCA) of the stroke patients and the control group. The pulsatility index of blood echogenicity (PIBE) was computed from the images, and PIBE from the patient group were higher than those from the control group, in RA (0.22±0.02 and 0.16±0.03) but not in CCA (0.35±0.02 and 0.32±0.01). Similarly, the fibrinogen concentrations of the patients were higher than those of the control group in RA (336±61 and 264±38 mg/dl) but not in CCA (340±126 and 257±43 mg/dl) except for a patient (555 mg/dl). The glucose concentrations of the patients were higher than those of the control group for CCA (129±32 and 92±16 mg/dl) but not for RA (128±39 and 98±13 mg/dl) except for a patient (210 mg/dl). Based on the present research, we suggest that EA can be estimated using ultrasound imaging in the RA and CCA, and that the in-vivo EA estimation would be contributed to the clinical applications for stroke patients.