PURPOSE: To assess the enhancement patterns of sellar and parasellar tumors at two-phase helical CT. MATERIALS AND METHODS: Thirty-two patients with pathologically proven sellar and parasellar tumors [meningioma (n=17), pituitary mocroadenoma (n=6), neurogenic tumor (n=5), cavernous angioma (n=1), chondrosarcoma (n=1), osteosarcoma (n=1), sphenoid carcinoma (n=1)] were included in this study. Two-phase helical CT was performed after the injection of 90 mL of contrast material at a rate of 3 mL/sec. Transverse helical CT scans were obtained during the early and late phases, with scanning delays of 30 and 120 seconds, respectively. Delayed coronal images were obtained after delayed axial images. Attenuation change and the enhancement patterns of the tumors were visually assessed; the former was also assessed quantitatively as the ratio of the CT number at late-phase axial and coronal scanning to that at early-phase scanning. RESULTS: Visual assessment of two-phase helical CT images revealed decreased attenuation in all 17 meningiomas, no change in all six pituitary macroadenomas and increased attenuation in 5 all five neurogenic tumors on late-phase axial scans as compared with early phase scans. Coronal images showed decreased attenuation in all 17 meningiomas, increased attenuation in all five neurogenic tumors and no change in four pituitary macroadenomas (66.7%). The ratio of CT numbers was significantly different between meningiomas, neurogenic tumors and pituitary macroadenomas(p<0.05). CONCLUSION: According to their histopathology, sellar and parasellar tumors showed characteristic enhancement patterns at two-phase helical CT. An analysis of the observed enhancement patterns can be useful in the differential diagnosis of juxtasellar tumors.