One of the important sources of patients microbial flora that is acquired during the hospital stay is the hospital environment. This acquired flora causes a disproportionately high number of the infections in patients who have leukemia. It is the purpose of this project to continuously monitor the patients environment and materials with which they come in contact so that sources of contamination can be eliminated. Some of these studies are performed in response to a perceived need. Regularly scheduled cultures which were temporarily discontinued due to lack of personnel, were resumed in February. These latter include room surfaces, food, air, water and equipment. Examples of sources of contamination which were detected last year are: thermometers, sandwiches supplied by a caterer, occasionally surface in rooms in the outpatient area and air.