Allergen-induced late airway responses are associated with increased numbers of airway eosinophils and basophils. The purpose of this study was to compare and contrast the effects of inhaled cysteinyl leukotrienes LTD₄ and LTE₄, which are released during allergen- induced airway responses, and allergen, on airway inflammatory cells. Fifteen subjects with atopic, mild asthma inhaled diluent, LTD₄, LTE₄, and allergen. Spirometry was performed for 7 h, and sputum inflammatory cells were measured before, 7 h, and 24 h after challenges. The maximum early percent fall in FEV₁ was 23.6 ± 1.4%, 21.6 ± 2.3%, 29.3 ± 2.4%, and 4.0 ± 1.1% after LTD₄, LTE₄, allergen, and diluent, respectively. Only inhaled LTE₄ and allergen significantly increased sputum eosinophils at 7 h and 24 h, and sputum basophils at 7 h. Six additional subjects underwent airway biopsies 4 h after inhalation. There were significantly more eosinophils in the lamina propria after inhalation of LTE₄ compared with LTD₄ and diluent (p < 0.05). These results suggest cysteinyl leukotrienes play a role in eosinophil migration into the airways in allergic asthma, and for the same degree of bronchoconstriction, inhaled LTE₄ causes more tissue and airway eosinophilia than LTD₄.