Pichia pastoris used to be referred to as a 'non-conventional' yeast. Not any more. In comparison to other yeast heterologous gene expression systems, notably including Saccharomyces cerevisiae, P. pastoris has many superior traits. For example, unlike fermentative yeasts, it conducts a predominantly respiratory mode of metabolism and is not subjected to a Crabtree effect. This means that it doesn't produce toxic ethanol and can grow to very high cell densities prior to switching on an inducible promoter (the AOX1 gene) for maximal recombinant protein production. The diversity of such proteins produced by expression strains of P. pastoris is quite amazing and this book describes detailed experimental protocols for a few of them (e.g. hookworm protein, botulinum toxin). The book additionally provides protocols for optimizing growth, transformation and gene expression of P. pastoris, as well as purification of secreted recombinant proteins. This is a stand-alone book meaning that researchers need not rely on information provided in the first (1998) edition. Although the publication was too late to include recent salient information on the P. pastoris genome, this does not detract from a book that will prove valuable to yeast molecular geneticists and biotechnologists.