The therapeutic potential of stem cells is enormous and largely untapped. Whilst to date very few of the new stem cell based therapies have passed the rigours of clinical testing, there are many such treatments poised to revolutionise modern molecular medicine. The use of stem cells in the clinic is not without its problems and until recently the use of embryonic stem cells presented several drawbacks. However with the advent of induced pluripotent stem cells a new wave of therapeutic potential has been unleashed. Research in Sheffield in the Centre for Stem Cell Biology has been at the forefront of efforts to understand the problems associated with the long term culture of human ES cells, but has also provided siginificant advances in our efforts in Sheffield to use stem cells in the clinic to treat a range of disesase including blindness, deafness, neurodegenerative disease and coronary heart disease. This presentation will give a background to ES cells, the problems assoicated with long term ES cell culture and how this might ultimately limit their clinical effectiveness, but at the same time highlight some of the recent discoveries and successes in Sheffield that are in the pre-clinical stages or actually in clinical use.