Transplantation of hepatocytes is a potentially very powerful therapeutic approach given their remarkable ability to regenerate the liver. The lack of proliferation of cultured hepatocytes, their poor viability after freezing and the scarcity of donors, however, have limited the application of the technique. To get around these problems, Sanjeev Gupta and co-workers have isolated epithelial progenitor/stem cells from foetal liver (seep. 2679). They show that these cells proliferate stably in culture for >40 divisions and coexpress markers characteristic of different liver cell lineages. The authors also show that the progenitor cells recover well after cryopreservation and differentiate to form mature hepatocytes when introduced into mice. Moreover, they demonstrate that the cells integrate into liver parenchyma and proliferate in vivo following liver injury. The cultured progenitor cells also successfully express exogenous genes introduced in adenoviral/lentiviral vectors. Gupta and co-workers therefore conclude that they represent an effective resource for both cell transplantation and gene therapy.