The treatment of craniopharyngioma becomes quite difficult when it extends into the third ventricle. In a 4-year-old boy, we encountered a large cystic craniopharyngioma which grew into the third ventricle. Initially, the tumor was successfully removed via a right transcallosal transchoroidal approach. A residual part seemed to have remained in the right perioptic region. Even though the patient had an episode of SIADH, his postoperative course was uneventful. He developed visual disturbance 4 months after the initial operation. CT and MRI revealed a large suprasellar mass. The tumor was totally resected via a right pterional approach. Careful follow-up disclosed again a small recurrent lesion in the anterior commisure. Gamma knife therapy was used to successfully reduce the volume of the tumor. The MIB-1 labeling index (LI) of the specimen taken at the time of the first operation was at 9.2% and that of the second operation at 21.2%. Recently, the importance of MIB-1 LI for assessing proliferative activity of this tumor was reported. In patients whose MIB-1 LI is higher, they have more significant rate of recurrence. Our results also indicate that in cases where MIB-1 LI indicates a high value, careful follow-up is necessary. Through fact of the necessity of two operations and additional gamma knife therapy, we would like to stress the importance of MIB-1 LI in indicating the proliferative activity of this tumor. These surgical procedures are presented here, and the role of MIB-1 LI in determining the proliferative activity of craniopharyngioma is also discussed.