Interleukin-11 (IL-11) is a multifunctional cytokine, which binds to specific cell surface receptors and initiates immune responses, epithelial cell proliferation, differentiation and apoptosis. Recently, it has been revealed that increased expression of IL-11 is associated with numerous diseases including cancer. IL-11 utilises the transmembrane β-subunit signal transducing receptor, GP130, which interacts with IL-11 and its α-subunit receptor (IL-11Ra). Of the three components of the IL-11 signalling complex, only GP130 and IL-11 have high-resolution crystal structures. Currently, the only structural data available for the entire signaling complex is derived from cryo-electron microscopy of the mouse IL-11/IL-11Rα/GP130 hexameric complex. The 30 Å resolution electron density map calculated from these images was interpreted using the crystal structure of the IL-6 signalling complex. Since no crystallographic structure for IL-11Rα is available our aim was to generate a high-resolution structure in order to begin to interrogate how the IL-11 signalling complex assembles and functions. To achieve this, we have undertaken crystal trials for the extracellular regions of human IL-11Rα and GP130, and have previously published the structure of IL-11. Small angle X-ray scattering analysis of the different components of the signalling complex together has also been performed. Our results will provide a platform for the design of therapeutics targeting this pathway.