Stem cells are unspecialized cells that are capable of becoming specialized cells each with new specialized cell function. They are classified into different types either by origin or potential of differentiation. Limbal epithelial stem cells are located in basal layer of limbal epithelium. They are adult and unipotent cells which have the ability to produce only cells of their origin. Limbal stem cell deficiency (LSCD) has been defined as destruction or dysfunction of stem cells located in limbal epithelium. This leads to failure of corneal epithelial regeneration and results in re-epitheliazation by conjunctival epithelium. This is accompanied by chronic inflammation, stromal scarring, neovascularization and persistent epithelial defect. LSCD may be primary as in aniridia or secondary as in Steven Johnson Syndrome (SJS), ocular cicatricial pemphigoid (OCP) and in chemical and thermal injuries. They are classified into partial and total LSCD.