This paper presents our preliminary experience with three-dimensional (3-D) treatment planning using the cine mode display of magnetic resonance imaging (MRI) for brain tumors. MRI images, viewed from the direction of the source of radiation, are reconstructed at consecutive 5 mm intervals and superimposed on the 3-D skin surface image. Tumors and normal structures can be visualized as is, without delineating them. Limitations of the technique are also discussed.