Elevated serum bromide concentrations following repeated halothane anaesthesia in a child. A 20-month-old child received 25 brief halothane general anaesthetics over a five-week period to allow cranial irradiation treatments for a posterior fossa ependymoma. Personality change during the last week of the treatment protocol raised the question of possible bromide intoxication. Serum bromide concentrations, using a gold chloride assay technique, were monitored at that time, and at four- and six-week intervals thereafter. Serum bromide concentrations demonstrated a four-fold change during this period ranging from peak levels of 2.2 mEq.L-1 (176 micrograms.kg-1) during the fifth week of treatment decreasing to less than 0.5 mEq.L-1 (less than 40 micrograms.ml-1) six weeks following the end of treatments. This demonstrates the possibility for repetitive, short halothane exposures to result in elevations of serum bromide and the potential of bromide intoxication in paediatric neuro-oncology patients. 