Immunocompromised patients require rapid diagnosis of infectious conditions, if treatment is to be effective. This paper describes rapid techniques for the identification of pathogens from transbronchial and other biopsy specimens. Included are rapid procedures for the following stains: Grocott-Gomori methenamine silver; Dieterle silver; periodic acid-Schiff; alcian blue; MacCallum-Goodpasture; and Kinyoun's acid-fast. The clinical usefulness of transbronchial biopsy is discussed.