The transforming growth factor-β (TGFβ) superfamily is encoded by 33 genes and includes TGFβ, bone morphogenetic proteins (BMPs) and activins. Although TGFβ is well recognized as a crucial regulator of immune responses, the immunoregulatory functions of other TGFβ family members are less clear. However, recent evidence suggests that BMPs and activins have important roles in regulating immune responses. In this Review, we briefly outline the signalling pathways of the TGFβ superfamily and discuss new insights into the immunoregulatory functions of BMPs and activins in the context of infection, inflammation and cancer.