Medulloblastoma, once a tumor with a dismal prognosis, is one of the most common primary brain tumors of childhood. As the methods of treatment have been continuously refined, the outcome has improved remarkably during the last few decades. The outcome of 78 medulloblastoma patients, which were managed from 1972 to 1992 at the Department of Neurosurgery of Seoul National University Hospital, were analyzed to calculate the 3-year and 5-year survival rates (3yS and 5yS). Of those, 52 cases which were treated after July 1982 were studied 1) to calculate the 3yS and 5yS, 2) to figure out the prognostic factors of survival, and 3) to investigate the role of adjuvant chemotherapy ('8-drugs-in-a-day' protocol: CCNU, cisplatin, vincristine, hydroxyurea, procarbazine, cytosine arabinoside, methylprednisolone and cyclophosphamide). The 3yS and 5yS of the 78 patients were 57.4% and 47.3%, respectively. Of the 52 patients treated after July 1982, the 3yS and 5yS were 67.8% and 64.1%, respectively. The latest recurrence was at 56 months after surgery. All the recurrences were within the risk period of Collins' rule. Of the prognostic factors studied by univariate analysis (age, sex, Chang's classification T- and M-stages, extent of surgical removal, and chemotherapy), Chang's classification M-stage and sex were the statistically significant factors (p = 0.028 and 0.024 respectively). On multivariate analysis, only the M-stage was statistically significant (p = 0.004). Adjuvant chemotherapy had different influences in different patient groups. Only in the 'poor risk' group, did adjuvant chemotherapy have a strong tendency to better outcome (p = 0.069). Further data collection and analysis will lead to better treatment modalities and better outcome for this most common primary malignant brain tumor in childhood.