Although conventional cancer therapies such as drug and radiation treatments may eradicate the majority of a tumour mass it has been suggested that a highly proliferative cell population remains. This led to the hypothesis that it is this population of cells, which are purely responsible for tumour growth. These cells have been termed cancer stem cells (CSCs) due to the fact that they share the properties of quiescence, self-renewal and differentiation with normal stem cells (Miller et al, 2005). If solely this population of cells drives the growth of cancer, then this may provide an explanation as to why many cancers are resistant to conventional cancer therapies and highlights the need for therapies targeted at cancer stem cells. The search for markers of these cells led to the discovery of a cell surface protein CD133 (Yin et al. 1997). CD133 is a five-transmembrane cell surface glycoprotein. Cells express CD133 shows self-renewal and proliferative features of stem cells and CSCs. The expression of CD133 disappears when the cells become committed to differentiation (Rizzo et al, 2005) suggesting that it is unique to stem cells. The aim of our research is to identify and quantify the expression of CD133 in normal and cancerous brain and prostate cell lines and tissues using quantitative RT-PCR. We aim to isolate mRNA from archival formalin-fixed paraffin-embedded (FFPE) tissues and assess CD133 expression in benign and cancerous prostate samples provided by the pathology laboratory (University Hospitals Morecambe Bay NHS Trust). The research aims to add further support for isolation of good quality mRNA from FFPE tissues. There is an abundant source of FFPE material available in laboratories and if such tissues are amenable to gene expression studies then this would open up a vast archive of material for analysis. Our results suggest that inactivation of CSCs may provide a novel therapeutic strategy in glioma and prostate tumours. Further study will focus on characterisation of the signalling pathways of CSCs in order to distinguish CSCs from normal stem cells.