From 2000-2007, we treated 14 patients (median age 5.8 years) with medulloblastoma (MB) with craniospinal irradiation (CSI) in the supine position for comfort, setup reproducibility and anaesthesia airway access. Acute toxicity included nausea/vomiting (N = 9), weight loss (median 10.3% (2.2-18.2), N = 10), lymphopenia (all), neutropenia (N = 3) and pancreatitis with Mallory-Weiss tear (N = 1). Five children required hospitalization during treatment. Chemotherapy was adjusted in 6, without CSI delay. After a median follow-up of 32.4 months (13.3-83.2), two patients recurred, two died of a second CNS malignancy, and one developed leukaemia. All others remain in complete remission. In this small series, CSI was delivered safely in the supine position with early outcomes in line with classical CSI literature.