In the present study, Phenolic compounds of ethanolic extracts of three organs (leaves, stem barks and roots) of Pterocarpus erinaceus were studied in UV-Visible Spectrophotometer. Furthermore the antiradical activity of these extracts was determined at room temperature by the method based on the reactivity of the extracts with a free radical, stable in solution, the l, l-diphenyl-2-picrylhydrazyl (DPPH). A synthetic antioxidant commonly used in the food and cosmetic industry, quercetin was used as reference to validate the antioxidant potential of phenolic extracts studied. The preliminary assessment of the phytochemical composition of this plant revealed the presence of polyphenols, tannins, free flavonoids, coumarins, terpenes, sterols and anthocyanins. The colorimetric assay revealed that the polyphenols are more concentrated in the bark of Pterocarpus erinaceus rod than in the leaf and root bark of the plant. Similarly, the stem bark of Pterocarpus erinaceus was more active than the leaf and bark of the root, although lower than the standard used (quercetin) activity. The evaluation of the granulometry influence revealed that the extraction solvent diffuses more easily inside the small particles to extract polyphenol molecules.