PURPOSE: To evaluate the MR findings of optic chiasmatic glioma (OCG). MATERIALS AND METHODS: MR images were reviewed in 14 patients with histologically proven OCGs and one with neurofibromatosis type 1 (male: female=8:7, mean age=8.5 years). Tumors were evaluated retrospectively with respect to their size, involvement of the optic pathway, transverse/vertical diameter ratio based on the coronal plane, signal intensities, enhancement pattern, and the presence of a cyst or calcification. RESULTS: Tumors was measured 1.7-5.5 (mean, 3.3) cm in maximum diameter. In ten patients, the optic tracts were involved, and in three, the optic nerves. In 12 patients, tumors had a transverse/vertical diameter ratio of over one, and showed iso (n=5) or low signal intensity (n= 10) compared with gray matter at T1-weighted imaging and high signal intensity (n=15) at T2-weighted imaging. Cyst formations were seen in eight patients, and tumors were enhanced strongly and homogeneously in nine and peripherally in four. In seven there was associated hydrocephalus, and in one, calcification. CONCLUSION: OCG is a suprasellar tumor which can extend into the optic pathway, has a transverse/vertical diameter ratio of more than one, and shows strong and homogeneous enhancement. These MR imaging findings are useful for the differentiation of OCG from other suprasellar tumors.