The objective of this project is to supply microbiologic diagnostic services of a high quality for the study of actual and potential infection of cancer patients with viruses, bacteria, mycoplasma and fungi. Further objectives are to study the patients' normal flora, food and environment in an effort to curtail acquisition of potentially pathogenic agents and supply support for evaluation of protective environments and various research investigations. A total of 14,355 patient samples were cultured for bacteria and/or mycoplasma and fungi during calendar year 1974. All microorganisms recovered were speciated and otherwise identified by serotyping or bacteriophage typing whenever possible. Emphasis was placed on enhancement of the recovery of anaerobes and mycoplasma. Development of resistance to commonly used antibiotics is continuously monitored. A total of 809 samples were evaluated for viral isolation, 5,215 sera for viral antibody titers, 394 examined by RIA and 98 by electron microscopy. Viral recovery rates from diagnostic samples vary seasonally between 5 and 10%. Approximately 75% of sera submitted have a 4-fold change in titer to one or more of the 20 antigens tested.