Objective      To investigate the difference of transcranial Doppler (TCD) sonography parameters in high altitude population with acute exposure

short time acclimatization and long-term chronic exposure.       Methods      The demographic data and TCD parameters of healthy lowlanders and high altitude population with acute exposure

short time acclimatization and long-term chronic exposure were collected. The mean velocity (V

m

)

systolic velocity (V

s

)

diastolic velocity (V

d

)

pulsatility index (PI) and resistant index (RI) of bilateral middle cerebral arteries (MCAs)

vertebral arteries (VAs) and basal arte

ry (BA) were analyzed by SPSS 19.0 for Windows.       Results      The V

m

V

s

V

d

PI and RI of the five arteries were significantly different in lowlanders and high altitude population with acute exposure

short time acclimatization and long-term chronic exposure (

P

0.01). The V

m

V

s

and V

d

of the five arteries increased substantially and the PI and RI of the arteries had a sharp drop upon initial acute high altitude exposure. The parameters mentioned above recovered gradually after 7 days’ acclimatization. As the occurrences of acclimatization and adaption during long-term live at plateau

the velocity of most arteries returned to the sea level

or even lower (MCAs and L_VA).       Conclusion      The influence of exposure time to high altitude on CBF

PI and RI is different. Hemodynamics has been modified though the vascular structures are repaired

which may increase the attack of cerebrovascular diseases.