Abstract: From Changchun and Wuhan regions, the writer collected two groups of 133 intact Chinese skulls, of which careful observations and measurements of the external apertures of the carotid canals and surrounding structures have been made. The results are as follows:
1. The form of the external aperture can be divided into three types: circular, oval and the form of a pumpkin seed. The circular form, accounting for 50.3 % is the commonest form, this result does not agree with the statement described in some textbooks.
2. The lengths of the external aperture range from 4 to 8mm. The average value is 6.03 mm on the right and 6.045 mm on the left. Its maximum length is equal on both sides ( 8mm ), Widths ranges from 4-11 mm. The average is 7.99 mm on the right and 8.06 on the left. The maximum width is the same on both sides (11 mm), while the minimum is 5 mm on the right and 4 mm on the left.
3. By comparision, the regional difference between the two groups of theskulls is significant statistically, e.g. in Changchun group the external aperture of carotid canal on the left side is longer and wider than those in wuhan group(t 2.16>1.98, p<0.05 and t 2.02>1.98, p<0.05 respectively ). While on the right side, the distance between the aperture and jugular fossa is much longer in wuhan group than those in Changchun(t 3.39 > 2.62, p<0.01).
4. The inferior apertures of tympanic canaliculus occur bilaterally in 122 skulls (91.7 %), and it is absent in a few skulls. It does not appear on right side of four skulls (0.3 %), and on the left side of seven skulls(0.5 %).
5. The jugular fossae vary in size and depth. 118 skulls (88.7%) are unequal on both sides. 115 skulls ( 86.5 %)have a larger and deeper fossa on the right side. In 15 skulls (11.3%)they are equal on both sides.

Key words: Skull; Carotid canal; Morphology