Objective.To determine the effectiveness of a UV-C-emitting device to eliminate clinically important nosocomial pathogens in a contaminated hospital room.Methods.This study was carried out in a standard but empty hospital room (phase 1) and in a room previously occupied by a patient with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus (VRE) infection (phase 2) in an acute care tertiary hospital in North Carolina from January 21 through September 21, 2009. During phase 1, 8 × 8 cm Formica sheets contaminated with approximately 104-105 organisms of MRSA, VRE, multidrug-resistant (MDR) Acinetobacter baumannii, or Clostridium difficile spores were placed in a hospital room, both in direct line of sight of the UV-C device and behind objects. After timed exposure, the presence of the microbes was assessed. During phase 2, specific sites in rooms that had housed patients with MRSA or VRE infection were sampled before and after UV-C irradiation. After timed exposure, the presence of MRSA and VRE and total colony counts were assessed.Results.In our test room, the effectiveness of UV-C radiation in reducing the counts of vegetative bacteria on surfaces was more than 99.9% within 15 minutes, and the reduction in C. difficile spores was 99.8% within 50 minutes. In rooms occupied by patients with MRSA, UV-C irradiation of approximately 15 minutes duration resulted in a decrease in total CFUs per plate (mean, 384 CFUs vs 19 CFUs; P < .001), in the number of samples positive for MRSA (81 [20.3%] of 400 plates vs 2 [0.5%] of 400 plates; P < .001 ), and in MRSA counts per MRSA-positive plate (mean, 37 CFUs vs 2 CFUs; P < .001).Conclusions.This UV-C device was effective in eliminating vegetative bacteria on contaminated surfaces both in the line of sight and behind objects within approximately 15 minutes and in eliminating C. difficile spores within 50 minutes.