The issue of beta cell regeneration in human pancreas is probably one of the most controversial aspects of type 1 diabetes research. In this review, we will first describe the known mechanisms underlying beta cell development and expansion in normal human pancreatic development because it is likely that such mechanisms might also play a role in beta cell regeneration. The sensu strictiori definition of beta cells implies replacement of lost beta cell mass by new beta cells. In our discussion, however, we will use the term in a more general way, defining as regeneration the formation of new beta cells, whether or not a loss of beta cells has actually occurred. The potential mechanisms of beta cell regeneration in the human pancreas will be discussed in the second part of this review. In particular, we will analyze beta cell regeneration through proliferation of beta cells, neogenesis from non-beta cell precursors, and transdifferentiation from alpha cells. In the third part of this review, we will explore the arguments for and against the ability of the human pancreas to regenerate functional beta cells in the context of type 1 diabetes and in other pathological conditions.