A recent paper by Noggle et al. reports an advance in human somatic cell nuclear transfer (SCNT). The ability to produce human pluripotent stem cells by transferring a somatic-cell nucleus into an enucleated oocyte would provide another way of generating patient-specific stem cells in addition to methods for converting somatic cells to induced pluripotent stem cells. (For a comparison of the two reprogramming strategies, see Nat. Biotechnol. 29, 701–705, 2011). Stem cell lines have been derived through SCNT for several mammalian species but not yet for human. In part, this can be explained by the scarcity of human oocytes available for research, but it's also possible that human cells are intrinsically more resistant to SCNT. Noggle et al. show that the tendency of human SCNT embryos to arrest at an early stage of development can be overcome if the oocyte nucleus is left in place rather than removed, allowing derivation of triploid stem cells. This suggests that the human nucleus provides unknown, essential factors that, once identified, could permit the generation of normal diploid stem cells. (Nature 478, 70–75, 2011)