OBJECTIVES: Cataplexy is a frequently observed symptom of narcolepsy which is treated mainly with antidepressants. However, as their success rate is very low, the unmet need is considerable. Sodium Oxybate is a novel treatment and the first product developed to treat cataplexy in patients with narcolepsy. Given the low prevalence and high unmet need, inclusion of sodium oxybate in the positive list of the Social Security Institution of Turkey is very important. This study aims at providing evidence about the cost effectiveness of sodium oxybate in Turkey. METHODS: As narcolepsy is a rare disease and sodium oxybate is the first product to treat the disease, there isn’t a global economic model to be adapted to the Turkish setting. That is why a simple decision model was developed to estimate the cost effectiveness. The results of the clinical trials of the product revealed that the annual number of cataplexy attacks prevented with placebo was 671, whereas the figure was 1,845 with sodium oxybate. As the Turkish guidelines for cost effectiveness analysis doesn’t allow using QALY data, only the number of prevented cataplexy attacks were used as an outcome measure. For the cost section, only the annual cost of sodium oxybate was used to calculate the incremental cost effectiveness ratio. The study was undertaken from the payer’s perspective. RESULTS: The cost per cataplexy attack prevented was found as 17.12 TL. As the incremental cataplexy attacks prevented was 1,174 annually, the total cost per prevented cataplexy attacks was estimated as 20.098 TL. Although Turkey doesn’t have an explicit threshold to be used in cost effectiveness decisions, this figure is acceptable given the fact that narcolepsy is a rare disease and there is a huge unmet need. CONCLUSIONS: Inclusion of sodium oxybate to the Turkish positive list of drugs is a cost effective option.