Abstract. Pediculosis capitis has a high prevalence especially in school children and this disease has also become a problem in developing and developed countries. Treatment that is based on synthetic chemicals in the market can cause poisoning and resistance. Therefore, an alternative compound from lemongrass (Cymbopogon nardus) containing citronella is sought. The purpose of this study was to assess the effectiveness of lemongrass leaves (Cymbopogon nardus) ethanol extract as a head Lice (Pediculus humanus capitis) exterminator. The subject of this study used 10 head lice in each group, the groups were the lemongrass leaves extract with 4%, 6%, and 8% concentration, and two control group, which used aquades and permethrin 5%. Within 5 hours of observation, the death of head lice was based on the total and the time. The result of one-way ANOVA analysis showed that the 8% concentration of lemongrass can kill 100% of the head lice in the second hour, the 6% concentration in the third hour, and the 4% concentration in the fourth hour, with the p value of =<0.000. Duncan test showed that 8% concentration of lemongrass was the most effective to kill head ice, however it is not equivalent to permethrin 5%. The 4%, 6%, and 8% concentration of Lemongrass ethanol extract are effective as an insecticide against head lice because it contains citronella that have insecticide effect.Keywords:  Citronella, Cymbopogon nardus, Insecticide, Pediculus humanus capitis.Abstrak. Pediculosis capitis memiliki prevalensi cukup tinggi terutama pada anak sekolah dan penyakit ini juga telah menjadi masalah di negara berkembang maupun negara maju. Pengobatan dengan obat kutu bahan dasar kimia sintetik yang beredar dipasaran dapat menyebabkan keracunan dan resistensi. Oleh sebab itu, dicari alternatif senyawa dari serai wangi (Cymbopogon nardus) yang mengandung sitronela. Tujuan dari penelitian ini adalah Menilai efektivitas ekstrak etanol daun serai wangi (Cymbopogon nardus) sebagai pembasmi kutu rambut (Pediculus humanus capitis). Subjek penelitian menggunakan 10 kutu rambut pada setiap kelompok yaitu kelompok ekstrak daun serai wangi dengan konsentrasi 4%, 6%, 8%, dan dua kelompok kontrol yaitu aquades, dan permethrin 5%. Dalam 5 jam di observasi kematian kutu rambut berdasarkan jumlah dan waktu. Hasil analisis one-way ANOVA bahwa serai wangi 8% dapat membunuh kutu rambut 100% pada jam ke 2, serai wangi 6% pada jam ke 3, dan serai wangi 4% pada jam ke 4, dengan nilai (p-value=<0,000). Uji Duncan menyatakan bahwa serai wangi 8% paling efektif membunuh kutu rambut namun, belum setara dengan permethrin 5%. Ekstrak etanol serai wangi dengan konsentrasi 4%, 6%, 8% efektif sebagai insektisida terhadap kutu rambut karena mengandung sitronela yang memiliki efek insektisida.Kata kunci:  Cymbopogon nardus, insektisida, Pediculus humanus capitis