An improved understanding of cellular activation, plasticity, interactions, targeting, differentiation and maturation, combined with the availability of recombinant growth factors, improved cell culture, separation and analytical systems have together brought new life to cellular therapies. Targeted T lymphocytes are being used, post-haematopoietic cell transplant, for prophylaxis and treatment of relapsed cancer, lymphoproliferative disease and viral infections. Pancreatic islet preparations have produced promising results in patients with refractory Type 1 diabetes, and stem cell plasticity is being exploited to repair disease-induced damage in a variety of tissues and organs. In the US, the rapid emergence of these therapies and reported adverse events have excited the interest of the Food and Drug Administration (FDA). The evolving regulatory strategy is likely to have profound effects on the future of this area of medicine.