AbstractThe cytologic features of a case of allergic bronchopulmonary aspergillosis (ABPA) are reported and the literature reviewed. The bronchial brushing smears in this case showed mucus that contained laminated aggregates of eosinophils with scattered Charcot‐Leyden crystals and fungal hyphae. These cytologic findings, overlooked by the initial examining pathologist, reflected the “mucoid impaction of bronchi” component of ABPA and are therefore diagnostic of ABPA. A cytologic diagnosis of a clinically unsuspected ABPA would lead to the correct treatment and prevent unnecessary surgery.