Purpose: The histone deacetylases (HDAC) inhibitor, valproic acid (VPA), is a common antiepileptic drug and is attractive for its broad range of therapeutic effects on many diseases. It has been employed as an inducer of pluripotency in some cultured cells. Conversely, VPA has also been employed as an inducer of in vitro differentiation in many other cells. Therefore, we employed WJMSCs as a cellular target to evaluate the differential effects of of VPA on potency state and differentiation level of Wharton’s Jelly mesenchymal stem cells (WJMSCs) in various concentrations and different culture mediums. Methods: The isolated WJMSCs were cultured in DMEM (MSC medium). According to previous protocols, WJMSCs were treated with 0, 0.5 and 1 mM VPA in MSC or embryonic stem cell (ESC) medium and 2 mM VPA in neural differentiation medium. Real-time polymerase chain reaction (PCR) and western blot analysis were performed for evaluating the expression of pluripotency markers. MTT and caspase assays were also performed on VPA-treated cells. Results: The expression of pluripotency markers and the viability of the WJMSCs – determined by MTT assay – were significantly increased after 0.5 mM VPA treatment in ESC medium. A 2 mM VPA treatment in neural differentiation medium significantly diminished the expression of pluripotency markers and the viability of WJMSCs. Conclusion: According to our results, both VPA concentration and the medium context can influence VPA effects on WJMSCs. The differential effects of VPA on WJMSCs can reflect its wide range of effects in the treatment of various diseases.