Objective: To review the mechanisms and important ICU-related aspects that contribute to the development of infection with antibiotic resistant (AR) pathogens; to describe its incidence; to summarize rates of resistance in the most common pathogens associated with hospital-acquired infections among critically ill patients; to provide an overview of the key principles of microbial surveillance of AR in the ICU, and to detail some cost considerations. Summary of findings: AR is one of the most pressing problems in healthcare, particularly in the ICU. Several factors unique to the ICU environment make patients in these units five to ten times more likely to develop hospital-acquired infections than patients on a general ward, and approximately half of these infections are caused by AR pathogens. The emergence of AR in the ICU has made treating these infections very difficult and, in some cases, even impossible. In addition to increasing the severity of infections, AR is driving up costs and as such it burdens indirectly the healthcare resources available for developing new antimicrobials. Conclusions: As the problem of AR is highly complex, a multifaceted approach is needed. A thorough understanding of the underlying grounds and the factors contributing to the further spread of these pathogens in hospitalized patients is of key importance when aiming to reverse, or at least to control this problem. In these times of tight budgets and increased workload, economic aspects of drug therapies should also be taken into account. Copyright © 2008, Nederlandse Vereniging voor Intensive Care. All Rights Reserved.