The inflammatory response is mediated by a family of chemotactic cytokines, designated chemokines. The receptor usage of the CXC chemokine granulocyte chemotactic protein‐2 (GCP‐2) was compared with that of interleukin‐8 (IL‐8) and epithelial‐cell‐derived neutrophil attractant‐78 (ENA‐78). Chemokine activities were evaluated by measurement of intracellular calcium increase and by chemotaxis and binding assays, using CXC chemokine receptor (CXCR)‐transfected cell lines. GCP‐2 was equally potent at inducing a rise in [Ca²⁺]_i in both CXCR1‐transfected and CXCR2‐transfected cells (minimal effective concentration 3 nM). IL‐8 augmented the [Ca²⁺]_i more efficiently in CXCR1‐transfectants than in CXCR2‐transfectants, whereas for ENA‐78, threefold higher concentrations were necessary to obtain a calcium response in CXCR1‐transfected cells than in CXCR2‐transfectants. GCP‐2 desensitized the calcium increase induced by IL‐8 in both CXCR1‐transfected and CXCR2‐transfected cells, but ENA‐78 only affected the IL‐8‐induced calcium response in CXCR2‐transfectants. The half‐maximal effective concentrations for migration of CXCR2‐transfectants in response to GCP‐2 and ENA‐78 were similar (0.1 nM), whereas GCP‐2 was tenfold more potent than ENA‐78 on CXCR1‐transfectants. Half‐maximal migration of CXCR1‐transfected and CXCR2‐transfected cells was obtained with IL‐8 at concentrations of no more than 0.01 nM. Radiolabeled IL‐8 could efficiently be displaced from CXCR2 by IL‐8, GCP‐2 and ENA‐78. In contrast, only IL‐8 and GCP‐2 but not ENA‐78, competed for ¹²⁵I‐IL‐8 binding to CXCR1. From these data, it can be concluded that, in addition to IL‐8, GCP‐2, but not ENA‐78, efficiently binds to both CXCR1 and CXCR2. The differential receptor usage of the structurally related ELR⁺CXC chemokines GCP‐2 and ENA‐78 is indicative of a different role in inflammatory reactions.