The flower parts of Paulownia coreana were extracted and the major essential oils composition and immunotoxicity effects were studied. The analyses were conducted by gas chromatography-mass spectroscopy (GC-MS) revealed that the essential oils of P. coreana. The P. coreana essential oil (PCEO) yield was 0.175%, and GC/MS analysis revealed that its major constituents were benzyl alcohol (13.72%), phenol, 3,4-dimethoxy-methyl ester (3.64%), phenol, 2-methoxy-3-(2-popenyl)-methyl ester (6.24%), 1,2,4-Trimethoxybenzene (8.32%), tricosane (3.28%), and pentacosane (3.26%). The essential oil had a significant toxic effect against early fourth-stage larvae of Aedes aegypti L with an LC(50) value of 31.64 ppm and an LC(90) value of 56.43 ppm. 1,2,4-Trimethoxybenzene was the most toxic among the major components with an LC(50) value near 23.1 ppm. The results could be useful in search for newer, safer, and more effective natural immunotoxicity agents against A. aegypti.