Treatment with O. basilicum suppressed Th2 cytokines’ (IL-4, 5, IL-8, IL-9, IL-11, 13 IL-25, and IL-33) gene expression; oxidant markers; total and differential WBC both in the blood and the BALF; reduced PLA2, IgE, and TP; alleviated mucus hyper-secretion and lung pathological changes (including goblet cell hyperplasia and airway responsiveness); and enhanced Th1 cytokine gene expression and Th1/Th2 balance but increased antioxidant marker levels in an animal model of asthma. This evidence concerns the gene IL9 and asthma.