Stem Cells are capable of self renewal and can differentiate into other lineages upon induction with specific growth factors and proteins. Mesenchymal stem cells obtained from various sources like adipose tissue, umbilical cord, bone marrow, umbilical cord blood have been reported to have stem cell characteristic features laid down by International Society for Cellular Therapy. Research so far deals with the differentiation and self renewal properties of stem cells, which needs to be understood further. Metallothionein, is a metal binding protein isolated from equine renal cortex and shown to be present in nearly all of our cells, with differential expression of it__ampersandsignrsquo;s isoforms. Apart from metal binding properties, this protein expression is deregulated in a variety of diseases and other treatment conditions. With respect to cancer biology, this protein expression is studied in almost all cancer types and results indicate the pivotal role of this protein in cancer. Certain cancers are associated with up-regulation while some types are associated with down-regulation. The localization of this protein has also reported changing between actively proliferating and normal cells. Given the importance of this protein in cancer biology, the role of this protein in stem cell renewal, as well as differentiation, is poorly understood. This review discusses about stem cells, - its type and differentiation; metallothionein - expression, function, review about different cancer types, role in angiogenesis and plausible role of this protein in the self-renewal and differentiation of stem cells.