The first examples of Pt complexes of the well known anti-epilepsy drug and histone deacetylase inhibitor, valproic acid (VPA), are reported. Reaction of the Pt(II) am(m)ine precursors trans-[PtCl2(NH3)(py)] and trans-[PtCl2(py)2] with silver nitrate and subsequently sodium valproate gave trans-[Pt(VPA−1H)2(NH3)(py)] and trans-[Pt(VPA−1H)2(py)2], respectively. The valproato ligands in both complexes are bound to the Pt(II) centres via the carboxylato functionality and in a monodentate manner. The X-ray crystal structure of trans- [Pt(VPA−1H)2(NH3)(py)] is described. Replacement of the dichlorido ligands in trans-[PtCl2(py)2] and trans- [PtCl2(NH3)(py)] by valproato ligands (VPA−1H) to yield trans-[Pt(VPA−1H)2(py)2] and trans-[Pt(VPA−1H)2 (NH3)(py)] respectively, significantly enhanced cytotoxicity against A2780 (parental) and A2780 cisR (cisplatin resistant) ovarian cancer cells. The mutagenicity of trans-[Pt(VPA−1H)2(NH3)(py)] and trans-[Pt (VPA−1H)2(py)2] was determined using the Ames test and is also reported.