Hemoglobin is a conjugated protein, consisting of the protein part called globin and the prosthetic part called heme. The hemoglobins differ depending on the type of polypeptide chains they are composed of. The normal hemoglobins are Hb-A (hemoglobin of adult), Hb-F (hemoglobin of fetal life) and Hb-A2 (hemoglobin of postnatal). Derivatives of hemoglobin are native hemoglobin, oxyhemoglobin, carboxy-hemoglobin, methemoglobin, hemochromogen, hematin, and hemin. This chapter covers the detection of hemoglobin and its derivatives, preparation of hemoglobin and derivatives, and preparation of hemin crystals.