Intensive care information systems (ICIS) implemented in intensive care unit (ICU) were shown to improve patient safety, reduce medical errors and increase the time devolved by medical/nursing staff to patients care. Data on the real impact of ICIS on patient outcome are scarce. This study aimed to evaluate the effects of ICIS on the outcome of critically-ill patients. From January 2004 to August 2006, 1,397 patients admitted to our ICU were enrolled in this observational study. This period was divided in two phases: before the implementation of ICIS (BEFORE) and after implementation of ICIS (AFTER). We compared standard ICU patient's outcomes: mortality, length of stay in ICU, hospital stay, and the re-admission rate depending upon BEFORE and AFTER. Although patients admitted AFTER were more severely ill than those of BEFORE (SAPS II: 32.1±17.5 vs. 30.5±18.5, p=0.014, respectively), their ICU length of stay was significantly shorter (8.4±15.2 vs. 6.8±12.9 days; p=0.048) while the re-admission rate and mortality rate were similar (4.4 vs. 4.2%; p=0.86, and 9.6 vs 11.2% p=0.35, respectively) in patients admitted AFTER. We observed that the implementation of ICIS allowed shortening of ICU length of stay without altering other patient outcomes.