Abstract: The invention provides novel JAK-3 inhibitors that are useful for treating leukemia and lymphoma. The compounds are also useful to treat or prevent skin cancer, as well as sunburn and UVB-induced skin inflammation. In addition, the compounds of the present invention prevent the immunosuppressive effects of UVB radiation, and are useful to treat or prevent autoimmune diseases, inflammation, and transplant rejection. The invention also provides pharmaceutical compositions comprising compounds of the invention, as well as therapeutic methods for their use.