Abstract. Aedes sp. is a vector of the dengue virus that causes Dengue Hemorrhagic Fever (DHF). Larvicides are the optimal method for controlling mosquito development. Temephos is a larvicidal agent of the organophosphate group which is reported to cause side effects and ecological hazards, as well as resistance based on reports in several country. This study aims to determine the larvicidal activity of the n-hexane fraction of Morinda citrifolia leaf ethanol extract on Aedes sp. The compound groups in the fraction were identified using TLC through UV light and spray reagents. There were six types of treatment including four concentration fractions (400, 600, 800, and 1000 ppm) as treatment, positive control (temephos 1%) and negative control 1% acetone solution. Twenty-five mosquito larvae of Aedes sp. tested for each treatment. Larval mortality was recorded and LC50 and LC99 values were analyzed using the probit. The results showed that the TLC test of the n-hexane fraction was positive for terpenoids, anthraquinones, phenols, tannins, and flavonoids. The results showed that the LC50 and LC99 values were 1040 ppm and 2439 ppm. Therefore, the n-hexane fraction of the ethanol extract had larvicidal activity on Aedes sp. with little toxicity. Abstrak. Aedes sp. merupakan vektor virus dengue penyebab Demam Berdarah Dengue (DBD). Larvisida merupakan metode yang optimal untuk mengendalikan perkembangan nyamuk. Temephos yang merupakan larvasida sintetik dapat menyebabkan resisten, efek samping dan bahaya ekologi. Kelimpahan agen hayati, efek toksik pada manusia yang minim, dan biodegradable menjadi tujuan utama perlunya pengembangan agen larvasida baru. Penelitian ini bertujuan untuk mengetahui aktivitas larvasida fraksi n-heksana ekstrak etanol daun mengkudu pada larva Aedes sp. Golongan senyawa pada fraksi diidentifikasi menggunakan KLT melalui pereaksi semprot. Terdapat enam jenis perlakuan diantaranya empat konsentrasi fraksi (400, 600, 800, dan 1000 ppm) sebagai perlakuan, kontrol positif (temephos 1%) dan kontrol negatif larutan aseton 1%. Dua puluh lima larva nyamuk Aedes sp. diujikan pada setiap perlakuan. Kematian larva dicatat dan nilai LC50 dan LC99 dianalisa menggunakan probit. Hasil penelitian menunjukkan bahwa uji KLT fraksi n-heksana positif mengandung terpenoid, antrakuinon, fenol, tanin, dan flavonoid. Hasil penelitian menunjukkan bahwa nilai LC50 dan LC99 adalah 1040 ppm dan 2439 ppm. Oleh karena itu, fraksi n-heksana dari ekstrak etanol memiliki aktivitas larvasida pada Aedes sp.