This AHRQ-funded multicenter prospective study used data from a previously described voluntary reporting system, the Intensive Care Unit Safety Reporting System (ICUSRS), to compare the types and severity of safety problems for medical and surgical ICU patients. Despite differences in the types of patients, the types of errors reported were generally similar between the two groups, with most errors being attributable to training and team system factors (such as communication). Prior studies using data from the ICUSRS have analyzed factors contributing to medication order entry errors and procedural errors.