Multidrug-resistant gram-negative bacteria are an emerging problem. The present article addresses 2 relevant questions: (1) should active surveillance be performed to identify patients colonized with multidrug-resistant gram-negative bacteria, and (2) should contact isolation precautions be taken with patients colonized or infected with multidrug-resistant gram-negative bacteria? Data and variables that are needed to scientifically answer these questions are reviewed, as are existing data on Pseudomonas aeruginosa, Enterobacteriaceae (Escherichia coli and Klebsiella species in particular), and Acinetobacter baumannii.