The Institute for Safe Medication Practices and the University of Illinois at Chicago, College of Pharmacy, undertook a hospital survey of medical-surgical hospitals to determine systems-oriented factors that allow the highest level of medication safety. The study incorporated a peer-reviewed and pretested questionnaire, which focused on critical information necessary to yield quality data for comparison. Through analysis, it was shown that over one third of all medication errors reported in the survey involve just six categories--allergies, insulin, heparin, opiates, PCA devices, and potassium concentrates.