The ascomycetous yeast Yarrowia lipolytica (formerly Candida, Endomycopsis, or Saccharomyces lipolytica) is one of the more intensively studied 'non-conventional' yeast species. This yeast is quite different from the well-studied yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe with respect to its phylogenetic evolution, physiology, genetics, and molecular biology. However, Y. lipolytica is not only of interest for fundamental research, but also for biotechnological applications. It secretes several metabolites in large amounts (i.e. organic acids, extracellular proteins) and the tools are available for overproduction and secretion of foreign proteins. This review presents a comprehensive overview on the available data on physiology, cell biology, molecular biology and genetics of Y. lipolytica.