It has been reported that Nigella sativa oil possesses anti-inflammatory and bronchodilator activities. Besides, non - toxic and wide margin of safety for therapeutic doses compared with Dexamethasone. This work aims to study the effect of Nigella sativa and Dexamethason on different immune and inflammatory parameters in a mouse model of allergic asthma. Mice sensitized intraperitoneally and challenged intratracheally with conalbumin were treated with Nigella sativa 24 hours after the first intratracheal challenge. Dexamethasone treated and naïve mice served as controls. The effect of Nigella sativa and Dexamethasone treatment on peripheral blood eosinophil count, IgG1 and IgG2a, cytokine profiles and lung inflammation were evaluated. Nigella sativa was significantly reduced peripheral blood eosinophil count, IgG1 and IgG2a levels, cytokine profiles and inflammatory cells in lung tissue. These effects were equivalent to the effects of Dexamethasone except unchanged IFN-y level. Nigella sativa exhibits anti-airway inflammation and immunoregulatory effect which may be useful for treatment of allergic asthma.