Drs Dellinger and Townsend stress that bundles should be evidence based, yet we have shown that with few exceptions, the elements of the 6-h sepsis bundle and ventilator-associated pneumonia bundle are not based on credible scientific evidence. There is surprisingly few data to support the contention that outcomes are improved when ICU bundles are rigorously followed. Before-and-after trials investigating effects of bundle implementation have reported reductions in mortality, apparently justifying bundle validity and calling for widespread adoption.4 However, before-and-after trials should be viewed with skepticism because they are plagued by publication bias, patient selection bias, temporal bias, and the Hawthorne effect. Furthermore, such studies provide compelling data for the concept that bundling is seriously flawed and that several individual elements of bundles do not improve patient outcome (except for the timely use of antibiotics). For example, in the Edusepsis study conducted in Spain, only early, broad-spectrum antibiotic treatment was associated with improved outcomes.5 It is noteworthy that in this study, mortality fell from 44% to 39% (P = .04) despite the fact that compliance with the 6-h sepsis bundle was only 10%, suggesting that factors other than bundle compliance were responsible for improved outcome. In the prospective, two-phase cohort study by Westphal et al,6 patients with severe sepsis/septic shock were resuscitated in accordance with the 6-h sepsis bundle. In the first phase of the study, patients were identified through usual clinical practice, whereas in the second phase, active surveillance for signs of sepsis risk was used. There were significant differences between phases I and II in the time required for the identification of severe/sepsis septic shock and in hospital mortality (61.7% vs 38.2%, P < .001); however, compliance with the 6-h sepsis bundle did not differ (32% vs 25%). Similarly, Shiramizo et al7 noted a fall in mortality in patients with severe sepsis/septic shock from 41.4% to 16.2% between 2008 and 2009, despite a decline in compliance with the 6-h sepsis bundle. It is likely that earlier identification of sepsis and earlier administration of antibiotics are responsible for the mortality difference in all the before-and-after studies, with the other elements either having no beneficial effect or possibly being harmful. Many basic questions regarding the resuscitation of patients with sepsis remain unanswered: What type of fluid should be used (is saline the right fluid)? What BP should be targeted? How best to titrate fluids?