Immobilization of children undergoing radiation therapy always requires anaesthesia. Deep sedation with continuous infusion of propofol and spontaneous breathing, (we call it ¿sedative anaesthesia'), may be an alternative to general anaesthesia with intubation and controlled ventilation. This clinical report deals with 155 anaesthetics performed in 11 consecutive paediatric oncology patients, mean age 30 months (range 19-42), who required radiation therapy for from seven to 33 consecutive days. Mean duration of anaesthesia was 18 ( +/- 11) mins. For induction, a loading dose of 3.6 (SD +/- 0.59) mg.kg-1 propofol was administered immediately followed by a continuous infusion of 7.4 ( +/- 2.2) mg.kg-1.h-1 for maintenance of anaesthesia. There were no complications of clinical importance involving respiration, circulation or neurology, except for one short episode of transient desaturation, which was managed by suctioning and changing head position. Children opened their eyes spontaneously four ( +/- 3.7) min after discontinuing the propofol infusion and could be discharged about 30 mins later. Tachyphylaxis or unpleasant side effects during and after anesthesia have not been observed. Sedative anaesthesia with propofol seems to be an excellent method to immobilize paediatric patients during radiotherapeutic procedures.