AbstractQuantitation of mast cells and eosinophils is of value in studies of allergic or parasitic tissue inflammation. We describe a new method that combines two reliable stains, astra blue and vital new red, to stain both mast cells and eosinophils in the same tissue section. The mast cells stain violet-blue and the eosinophils bright red. Because this method stains both cells in tissue that has been fixed with form01 saline or buffered formaldehyde, it can be used on archival tissue that has undergone standard fixation. The minimal staining of the background makes quantitative studies of both cells simple, even at low magnification. (The J Histotechnol16:143, 1993)