IMiDs belong to a new pharmalogical class, whose principal therapeutic agents are the thalidomide and the lenalidomide. They have immunomodulatory and antiangiogenic properties, as well as a direct effect on tumor cells. Thalidomide and lenalidomide were first approved for multiple myeloma, and in 5q-myelodysplastic syndrome for lenalidomide. Several studies have shown the efficacy of these drugs in others hematologic malignancies. A third component has been developed, the pomalidomide, which may be more effective in certain indications. Here we present an overview of IMiDs in hematology, including mechanisms of action and known significant side effects.