The intensive care unit (ICU) creates the unique situation of subjecting highly susceptible patients to a variety of invasive procedures that are concentrated in a small unit. Effectively providing life-saving care is considered more important than other measures, such as infection control. Nevertheless, it is frustrating to lose a patient due to a sepsis that could have been prevented by simple hygienic arrangements, the application of aseptic techniques, and infection control measures. There is some confusion about the necessity and efficacy of many of these prescriptions, and some of them must certainly be considered rituals: only controlled studies demonstrating the influence of the specific measure on the infection rate will give a decisive answer about usefulness. Most factors determining the occurrence and transmission of infections lie with the patient's resistance and treatment, but technical, diagnostic, and curative measures may also influence the infection rate. Facilities, techniques followed, and prescribed procedures may differ from hospital to hospital. If we want to draw a conclusion from the comparison of infection rates in different ICUs, it is desirable to compare not only the different preventive measures in nursing procedures and techniques, but also the organization and structure of the units. Therefore, our committee decided to study the hygienic situation of ICUs before elaborating a practicable and valuable system for the registration of nosocomial infections. The study was not limited to the small group of interested teaching hospitals with high standards, but rather, was extended to all Austrian (A) ICUs and a significative sample of German (D) and Belgian (B) ICUs.