New palladium complexes of chloroquine (CQ) and clotrimazole (CTZ) have been prepared, characterized, and evaluated against four tumor cell lines in vitro. [Pd (CQ)2Cl2] (1) was synthesized by the reaction of PdCl2(CH3CN)2 with CQ, and the [Pd (CTZ)2Cl2] (2) complex by a similar reaction. The new compounds were characterized by a combination of FAB-MS (fast atom bombardment-mass spectrum), elemental analysis, molar conductivity, IR, and NMR spectroscopy. The solid-state structure of 2 has been determined by X-ray crystallography. 2 crystallizes in the monoclinic space group P(2(1)/c), with a = 21.100(4) A, b = 13.408(3) A, c = 22.642(5) A. The structure refinement converged at R1 = 0.0728, wR2 = 0.1918. The cytotoxicity of these two complexes for the tumor cell lines, PANC-1, SKBR-3, MDA-MB231 and HT-29, was compared with that of the original ligands. Ligation of palladium to CTZ led to an increase in the IC50, although a three-fold reduction in the IC50 of CQ was observed on ligation to the metal when tested against the MDA-MB231 cell line.