Thirty patients with intraocular tumors were examined with MRI. A clear demarcation was seen between the melanomas and other intraocular structures such as sclera, vitreous and ciliary body. Retinal detachment, hemorrhage or choroidal-retinal layer could be seen separated from the tumor. In all our patients investigated with MRI the absence of extraocular melanoma tissue was confirmed by histopathology or by the findings during surgery. The demarcation between tumor and sclera seemed more sensitive in MRI than in ultrasonography in establishing extrascleral extension. Our study showed that MRI can be a valuable addition to ultrasonography in detecting intraocular tumors or tumor simulating lesions.