It has been postulated that inhibition of Histone Deacetylase (HDAC) can restore normal acetylation of histone proteins and transcription factors, and to be of benefit in the treatment of cancer. So, this study aimed at assessing the response to histone deacetylase inhibitor valproic acid combined with conventional chemotherapy versus conventional chemotherapy alone in Egyptian Acute Myeloid Leukemia (AML) patients. Thirty newly diagnosed AML patients were divided into 2 groups. Group 1 consisted of 15 AML patients received conventional chemotherapy while group 2 consisted of 15 AML patients received valproic acid 40 mg/kg for 7 days and conventional chemotherapy. Ten healthy persons of matched age and sex were considered group 3 (controls).