Agaricus bisporus (button mushroom) is the most popular variety grown and consumed the world over. In India production is produced throughout year due to technology development. Button mushroom is rich in amino acid. When an essential amino acid is not provided in adequate amounts in diet protein synthesis is limited to the rate at which essential amino acid is available. Essential amino acid than become limiting amino acids. In present study A. bisporus studied for limiting essential amino acid influenced by pyrites treatment. Best result were obtained by pyrites treatment.