Embryonic stem (ES) cells are expected to become a cell source and biological delivery system for use in a variety of neurodegenerative diseases, and will likely play a role in the development of novel cell-based therapies for these indications. These applications require the in vitro differentiation of ES cells into stable, safe and functional neural cell populations. Initial experiments with mouse ES cells are now in the process of being translated and developed into studies on human (h)ES cells. Despite their potential, several hurdles must be overcome to render hES cells a reliable and efficient system to produce cell types for therapeutic application and as a model system for therapy development. This review discusses the current state of research into hES cells, with an emphasis on neurodegenerative diseases.