To the Editor.— We cannot wholly agree with Dr. Carl W. Walter (229:578, 1974) on all points. We do agree that, during outbreaks of nosocomial infection, cultures of environmental sites that are implicated epidemiologically may be quite useful in identifying and removing a contaminated inanimate source of infection. In addition, environmental cultures (or use of spores for microbiological monitoring) are of value as a means of infection control in other circumstances, including (1) regular monitoring of sterilization procedures, (2) monitoring disinfection of critical patient-care equipment that cannot be sterilized, (3) educating infection control and microbiology personnel, (4) motivating and training hospital staff members, and (5) investigating the epidemiology of nosocomial infections. Routine sterility testing of commercial products in hospitals is not recommended because of the low frequency of such contamination and the difficulty and expense of adequate sterility testing. However, we are not convinced that routine culturing of the general