ABSTRAK Penggunaan antibiotik yang tidak rasional dalam pengobatan penyakit infeksi dapat menyebabkan munculnya strain bakteri yang resisten terhadap antibiotik seperti bakteri Methicillin Resistant Staphylococcus aureus (MRSA). Penelitian ini bertujuan untuk mengetahui aktivitas antibakteri minyak atsiri serai wangi (Cymbopogon nardus (L.) Rendle) terhadap bakteri MRSA serta mengukur besar diameter zona hambat yang dihasilkan pada uji aktivitas antibakteri. Penyulingan minyak atsiri serai wangi dilakukan dengan metode destilasi uap-air. Karakterisasi minyak atsiri serai wangi meliputi penentuan berat jenis, indeks bias dan kelarutan minyak dalam etanol 80% untuk menentukan mutu minyak atsiri serai wangi yang dihasilkan. Penentuan uji aktivitas antibakteri minyak atsiri serai wangi dilakukan dengan metode Kirby Bauer pada konsentrasi minyak 2,5; 5; 10; 15; 20; dan 25%. Kontrol positif yang digunakan yaitu ciprofloxacin 5 µg dan kontrol negatif yang digunakan yaitu tween 80 konsentrasi 10%. Hasil dari penyulingan minyak atsiri serai wangi diperoleh nilai randemen minyak atsiri sebesar 0,5%. Hasil karakterisasi minyak atsiri yang diperoleh pada penelitian ini yaitu minyak atsiri serai wangi memiliki berat jenis sebesar 0,904, indeks bias sebesar 1,470 dan kelarutan dalam etanol 80% menghasilkan larutan berwarna kuning keruh. Hasil uji aktivitas antibakteri menunjukkan bahwa minyak atsiri serai wangi pada konsentrasi 2,5 dan 5% tidak menghasilkan aktivitas antibakteri, sedangkan konsentrasi 10; 15; 20; dan 25% menghasilkan diameter zona hambat rata-rata sebesar 13,20; 12,55; 11,68; dan 10,03 mm. Kontrol positif ciprofloxacin 5 µg menghasilkan diameter zona hambat sebesar 28,54 mm, sedangkan kontrol negatif tween 80 konsentrasi 10% tidak menghasilkan aktivitas antibakteri. Hasil uji aktivitas antibakteri membuktikan bahwa minyak atsiri serai wangi memiliki aktivitas antibakteri terhadap bakteri MRSA. Kata kunci : Methicillin Resistant Staphylococcus aureus, Cymbopogon nardus (L.) Rendle, destilasi uap-air, karakterisasi minyak dan Kirby Bauer ABSTRACT Irrational use of antibiotics in the treatment of infectious diseases can cause the emergence of bacterial strains that are resistant to antibiotics such as the Methicillin Resistant Staphylococcus aureus (MRSA) bacteria. This study aims to determine the antibacterial activity of citronella essential oil (Cymbopogon nardus (L.) Rendle) against MRSA bacteria and measure the diameter of the inhibitory zone produced in the antibacterial activity test. Distillation of fragrant citronella essential oil is carried out by the steam-water distillation method. Characterization of essential oils includes determining the specific gravity, refractive index and solubility of oil in 80% ethanol to determine the quality of the fragrant citronella essential oil produced. Determination of antibacterial activity test for citronella essential oil was carried out by Kirby Bauer method at oil concentration 2,5; 5; 10; 15; 20; and 25%. The positive control used was ciprofloxacin 5 µg and negative control used, namely tween 80 concentration of 10%. The yield of fragrant citronella essential oil distillation was obtained by the value of essential oils by 0.5%. The results of volatile oil characterization obtained in this study are citronella essential oil has a specific gravity of 0.904, the refractive index is 1.470 and the solubility in 80% ethanol produces a cloudy yellow solution. The results of the antibacterial activity test showed that citronella essential oil at a concentration of 2,5 and 5% did not produce antibacterial activity, while the concentration of 10; 15; 20; and 25% produce an inhibition zone diameter of an average of 13.20; 12,55; 11,68; and 10.03 mm. The positive control of ciprofloxacin 5 µg results in a diameter of the inhibition zone of 28.54 mm, while the negative control tween 80 concentrations of 10% did not produce antibacterial activity. The results of the antibacterial activity test prove that citronella essential oil has antibacterial activity against MRSA bacteria. Keywords: Methicillin Resistant Staphylococcus aureus, Cymbopogon nardus (L.) Rendle, steam-water distillation, oil characterization and Kirby Bauer