Histone deacetylases (HDACs) inhibitors are disclosed. The HDACs inhibitors possess cytotoxicities to various cancer cell lines. They are useful for treating a tumor associated with deregulation of the activity of histone deacetylases in a subject in need thereof, in one embodiment, the HDACs inhibitors of the invention are useful for treating glioma, breast cancer, colon cancer, targe cell lung cancer, adenocarcinoma of the lung, small cell lung cancer, stomach cancer, liver cancer, ovary adenocarcinoma, pancreas carcinoma, prostate carcinoma, promyiocytic leukemia, chronic myelocytic leukemia, or acute lymphocytic leukemia in a subject in need thereof.
