Tujuan dari penelitian ini untuk mengetahui (1) perbedaan mortalitas larva nyamuk Culex quinquefasciatus yang diberikan ekstrak daun jarak pagar (Jatropha curcas L.) pada konsentrasi yang berbeda (2) kosentrasi ekstrak daun jarak pagar (Jatropha curcas L.) yang diperlukan untuk membunuh 50% (LC 50) larva nyamuk Culex quinquefasciatus. Penelitian ini merupakan penelitian true experimental dengan rancangan acak lengkap (RAL). Sampel dalam penelitian ini adalah larva nyamuk Culex quinquefasciatus instar III. Jumlah perlakuan dalam penelitian ini sebanyak 5 (0%,15%, 30%, 45%, dan 60%). Data dianalisis menggunakan uji Anava One Way. Hasil penelitian menunjukkan bahwa (1) terdapat perbedaan mortalitas karva nyamuk Culex quinquefasciatus yang diberikan ekstrak daun jarak pagar dengan konsentrasi berbeda (2) berdasarkan hasil analisis probit, ekstrak daun jarak pagar menunjukan bahwa LC50 berada pada konsentrasi 35,867%.Kata Kunci : Ekstrak daun jarak pagar, larva nyamuk Culex quinquefasciatus, mortalitas Abstract The aim of this research were to determine (1) the difference of the mortality of Culex quinquefasciatus mosquito larvae which was given various concentration of Jatropha curcas L. leaf extract (2) the conceration of Jatropha curcas L. extract required to kill 50% (LC50) Culex quinquefasciatus mosquito larvae. This research was a true experimental research with complete randomized design (CRD) as the research method. Culex quinquefasciatus instar III were used as the sample in this reasearch. There were five different given treatments of giving various concentration of Jatropha curcas L. leaf extract, such as 0%, 15%, 30%, 45%, and 60%. The data were analyzed using One Anava test. The result showed that (1) there was a difference of mortality of Culex quinquefasciatus mosquito larvae was given Jatropha curcas L. extract with various concentration (2) based on the probit analysis Jatropha curcas L. leaf extract Jatropha curcas L showed that LC50 that in concentration 35.876%.keyword : Culex quinquefasciatus mosquito larvae, Jatropha curcas L. leaf extract, mortality