p46 Shc and p52 Shc become heavily tyrosine phosphorylated in response to interleukin 3 (IL-3) treatment. We have investigated the potential of Shc to integrate IL-3 signalling pathways and demonstrate that Shc associates with the β subunits of the human (βc) and murine (Aic2A) IL-3 receptors, SHIP and Gab2 following IL-3 stimulation. The interaction between Shc and the IL-3 receptor β chains was direct, mediated by both the SH2 and PTB domains. Interaction with SHIP was via the Shc PTB domain and the Shc SH2 domain mediated the interaction with Gab2. Phosphopeptide competition studies suggest that the SH2 domain interacts primarily with tyrosine 612 of βc (610 of Aic2A), and the PTB domain with tyrosine 577 of βc (575 of Aic2A). PTB binding to IL-3R β chains was of highest affinity, and appeared to play the primary role in binding. These findings suggest that Shc may play an important role in coordinately integrating IL-3 signalling pathways.