Four new manganese(III) Schiff base complexes (1-4) were synthesized and characterized. The complexes have general formula [MnClL x ] in which L represents a Schiff base ligand derived from condensation of meso-1,2-diphenyl-1,2-ethylenediamine with salicylaldehyde or its 3-OMe-, 5-Br-or 5-OMe-derivatives (x = 1-4, respectively). The crystal structure of [MnClL 1 ](1) was characterized by X-ray crystallography. The in vitro anticancer activity of these complexes was evaluated by MTT and apoptosis assays against human breast (MCF-7) and liver (Hep G2) cancer cells. The complexes exhibited considerable antiproliferative activity against both cell lines (IC 50 = 10.8-21.02 µM) comparable to cis-platin, except 4 (MCF-7). The highest activity was found for 1 with IC 50 values of 13.62 µM (MCF-7) and 10.8 µM (Hep G2). Flow cytometry experiments showed that 1 induced apoptosis on MCF-7 tumor cell line. Docking simulations using AUTODOCK were also carried out. The results showed that all complexes fitted into the minor groove region of DNA.