To evaluate the efficacy and side-effect profile of offlabel sodium oxybate (gamma hydroxy butyrate) therapy in severe childhood narcolepsy-cataplexy. Retrospective; chart review. A multidisciplinary tertiary sleep center. A group of eight children with severe narcolepsy-cataplexy diagnosed on the basis of clinical history, nocturnal polysomnography and the multiple sleep latency test were studied. A modified Epworth Sleepiness Scale and an arbitrary cataplexy severity scale (1=minimal weakness, 2= voluntarily preventable falls, 3= falls to the ground) were utilized. Sodium oxybate therapy; concurrent medications were maintained. Before sodium oxybate therapy, all subjects had suboptimally controlled sleepiness and cataplexy. Following treatment with sodium oxybate, 7/8 subjects (88%) improved. Cataplexy frequency decreased from a median of 38.5 to 4.5/ week (p=0.0078). Cataplexy severity decreased from 2.75 to 1.75 (p = 0.06). The Epworth Sleepiness Scores improved from a median of 19 to 12.5 (p= 0.02). Suicidal ideation, dissociative episodes, tremor and constipation occurred in one subject each and terminal insomnia in two. Three of the 8 (38%) discontinued therapy. Two stopped the drug owing to side effects and one due to problems with postal delivery of the medication. This is the first report on sodium oxybate therapy in childhood narcolepsy-cataplexy. Our finding of improvement in cataplexy and sleepiness suggests that this medication is effective in treating severe childhood narcolepsy-cataplexy.