The emphasis of this lab manual is on the basic principles of diagnostic microbiology for students preparing to enter an allied health field. Students are led through a series of exercises that allow them to learn basic microbiology techniques and to practice safety in the laboratory and hospital environment. It remains oriented primarily toward meeting the interests and needs of those who will be directly involved in patient care and who wish to learn how microbiological principles should be applied in the practice of their professions. The authors have emphasized the purposes and function of the clinical microbiology laboratory in the diagnosis of infectious diseases. The exercises illustrate as simply as possible the nature of laboratory procedures used for isolation and identification of infectious agents as well as the principles of asepsis, disinfection and sterilization. Attention is given to the role of the health professional in regard to appropriate collection of clinical specimens and the applications of aseptic and disinfectant techniques as they relate to patient care.