The aim of this study was to evaluate the in vitro cytotoxic activity of methanolic extract (SBEM ? Stem Bark-Ethanolic-Methanolic), acetonic (SBEA – Stem Bark-Ethanolic-Acetonic) and acetate (SBET – Stem Bark-Ethanolic-Acetate) fractions of the stem bark?s crude ethanolic extract of a kind of plant from Brazilian Cerrado vegetation against a model of murine breast cancer (Ehrlich cancer cell line) and against normal cells in order to select the one with a better Index Selectivity (IS) for posterior studies. Ehrlich cancer cells (1x105cells/well) were treated with SBEM, SBEA and SBET, respectively for 48h at 7 different concentrations between 25 µg to 2000 µg mL-1. MTT assay was utilized to determine the cytotoxicity of each fraction of extract by estimating the concentration, which inhibits 50% of cellular viability (IC50). SBEM presented IC50 of 158 µg mL-1 ± 15; SBEA presented IC50 of 71 µg mL-1 ± 22; and SBET presented IC50 of 56 µg mL-1 ± 17. Comparing IC50 of these three fractions, SBET showed to be more cytotoxic against Ehrlich?s tumor cells than the other two. Now, the next step will be to study the cytotoxicity of the extracts in normal cells to evaluate the IS.