We have investigated the contribution of integrin α₄β₇ to human peripheral blood eosinophil adhesive interactions. Immunofluorescence and flow cytometry demonstrated constitutive expression of α₄β₇ by eosinophils. Expression of α₄β₁ or α₄β₇ was not enhanced by eosinophil activation with platelet‐activating factor (PAF). Expression of α₄β₇ was confirmed by immunoprecipitation of ¹²⁵I‐labelled lysates analysed by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE). Approximately 20% of unstimulated eosinophils were adherent to L1‐2 cells transfected with vascular cell adhesion molecule‐1 (VCAM‐1) cDNA, while very few resting eosinophils adhered to mouse mucosal adressin cell adhesion molecule‐1 (MAdCAM‐1) transfectants. Binding of unstimulated eosinophils to VCAM‐1 transfectants was inhibited by HP1/2 (an antibody that blocks both α₄β₁ and α₄β₇ functions), but not Act‐1, an α₄β₇ monoclonal antibody (mAb). PAF stimulation resulted in increased binding of eosinophils to MAdCAM‐1 transfectants, which was inhibited by both HP1/2 and Act‐1. In contrast, PAF did not enhance binding to VCAM‐1 transfectants, although binding of PAF‐stimulated eosinophils to VCAM‐1 could be partially inhibited by Act‐1. Stimulation of eosinophils with the β₁‐activating mAb TS2/16 resulted in enhanced binding of eosinophils to both VCAM‐1 and MAdCAM‐1 transfectants. The increased binding was largely α₄β₇‐dependent. Unstimulated eosinophils bound to soluble recombinant human (rh)VCAM‐1 and fibronectin (Fn), coated on 96‐well plates in a dose‐dependent manner. Binding was inhibited by HP1/2 and 4b4, an anti‐β₁ mAb, but not by Act‐1. TS2/16 treatment increased adherent cell numbers and this enhanced binding was inhibited by Act‐1. We have therefore confirmed that α₄β₁ is functionally active on unstimulated eosinophils. In contrast, PAF‐induced enhancement of eosinophils binding to VCAM‐1 or MAdCAM‐1 was α₄β₇‐dependent. In addition, treatment with TS2/16 resulted in a α₄β₇‐dependent enhancement of eosinophil binding to VCAM‐1, MAdCAM‐1 and Fn. We therefore hypothesize that α₄β₇ may have an important role in eosinophil localization in diseases such as asthma and inflammatory bowel disease.