This textbook is the descendant of Volume One of the text by Mackie and McCartney which was first published in 1925. It is a book for medical microbiologists and microbiology MLSOs (and trainees) that details laboratory methods for the identification of infectious organisms. It is organized on a taxonomic basis: each organism has its own chapter in which all relevant techniques are described. This edition includes: new methods of identification featured, including PCR and related techniques; description of use of diagnostic kits, which are of increasing importance; a new chapter on helminthology; a removal of many old-fashioned techniques.