Background: The expanded transsphenoidal approach is used to excise the tumour in clival region, which is a difficult point of neurosurgery. Preoperative imaging evaluation has important significance for the development of surgical approach. Objective: The aim of this study was to evaluate the relationship between the sphenoidal sinus and clivus with CT (computed tomography), in order to provide a basis for the design of transsphenoidal approach to clival region. Methods: A total of 30 patients underwent thin head scan with 64-slice spiral CT, the sagittal images were reconstructed in AW 4.2 workspace. The incidence of clival recess, the area of sphenoidal sinus, the thickness and height of clivus behind sphenoidal sinus, and the relationship between them were analyzed in the median plane. Results: The thickness of clivus in 73% of patients was less than 6.0 mm, while the height of that was more than 9.0 mm. The incidence of clival recess was 63%. When the clival recess was existed, the thickness of clivus was 1.8 +/- 1.1 mm. The thickness of clivus in 10% of patients was less than 6.0 mm, while the clival recess was not existed. There was negative linear correlation between the area of sphenoidal sinus and the thickness of clivus. The thickness of clivus in 17% of patients was more than 6.0 mm, while the area of sphenoidal sinus was more than 3 cm(2). Conclusion: The assessments of thickness of clivus and clival recess with CT are useful to design the individualized transsphenoidal approach to clival region.