Depsipeptides and congeners thereof are disclosed having structure (I), wherein m, n, p, q, X, R1, R2 and R3 are as defined herein. These compounds, including FR901228, have activity as, for example, immunosuppressants, as well as for the prevention or treatment of patients suffering or at risk of suffering from inflammatory, autoimmune or immune system-related diseases including graft-versus-host disease and enhancement of graft/tissue survival following transplant. Also provided are methods for inhibiting lymphocyte activation, proliferation, and/or suppression of IL-2 secretion.