BACKGROUND Recent studies have provided substantial evidence on the potential for healthcare associated infections (HAIs) due to contaminants in the environment such as floors, etc. In this study we compared environmental bacterial contamination in a pediatric intensive care unit (PICU) before and 48 hours after a terminal cleaning. METHODS Using data from a previous study by the authors we established the 10 most contaminated sites in the PICU (bed rails, floor by sink, stethoscopes, return air ducts, bath basin, computer keyboard and mouse, cell phones, Pyxis touch screen, equipment handles, beside table). These sites were sampled in triplicate using sterile transport swabs and were use to inoculate Mannitol Salt Agar (for Staphylococci), CHROMagar (for methicillin resistant S. aureus (MRSA)), Pseudomonas Isolation Agar (for Pseudomonas sp.), Eosin Methylene Blue (for enteric bacteria), and Tryptic Soy Agar (TSA) (for non-specific bacteria). Samples were obtained before and 48 hours after a terminal cleaning. RESULTS Of the samples collected in the PICU before the cleaning 14 (47%) were positive for S. aureus, 7 (23%) for MRSA, 6 (20%) for enterics, 0 (0%) for Pseudomonas, 13 (43%) TSA. Forty-eight hours after the terminal cleaning 7 (23%) were positive for S. aureus, 0 (0%) for MRSA, 3 (10%) for enterics, 0 (0%) pseudomonas, 11 (37%) for non-specific bacteria. The most contaminated areas were the floors near the sink, and the return air ducts (p CONCLUSIONS Overall contamination was significantly reduced by terminal cleaning (p