Eucalyptus oils are widely used as spices, perfume industrial materials, food flavorings, and medicines. Several types of Eucalyptus oils also have insecticidal activity and as carminative. This study investigated the chemical composition, insecticidal (larvicidal and repellent) activity of E. urophylla oil against filarial mosquito Culex quinquefasciatus. E. urophylla oil was obtained from fresh leaves by water-steam distillation with oil yield 1.08%. E. urophylla oil in this study had no color (clear), has odor (typical eucalyptus), with specific gravity 0.941; refractive index 1.465; miscibility in 70% ethanol 1 : 3; and optical rotation (-) 5.83°. The major compounds of the oil were α-pinene (11.73%), 1,8-cineole (49.86%), β-ocimene (6.25%), γ-terpinene (9.11%), and α-terpinyl acetate (7.63%). The result showed the excellent insecticide activity against C. quinquefasciatus. The oil provided larvicidal activity with LC50: 80.21 ppm and LC90: 210.18 ppm, and repellent activity with IC50: 0.82% and IC90: 4.88%. The present study showed the effectiveness of E. urophylla as natural insecticide against C. quinquefasciatus, the mosquito vector of filariasis.