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This invited commentary is not so much about science as it is about our lack of knowledge in transfusion medicine and perioperative hemostasis and about how this lack of knowledge affects our practice. As suggested by the title, the intent of this discourse is to be provocative but certainly not contemptuous. Despite widespread collection and administration of red blood cells (81 million units are collected annually worldwide; http://www.who.int/bloodsafety/FactFile2009.pdf), transfusion practice is based on meagre good quality evidence. The most recent search of the Cochrane Database of Systematic Reviews identified a mere 17 trials involving 3,746 patients randomized to interventions based on a clear ‘‘transfusion trigger’’. The authors concluded that restrictive transfusion strategies reduced the risk of receiving a red blood cell (RBC) transfusion and did not appear to impact on the rate of adverse events compared with liberal transfusion strategies. In fact, in the Transfusion Requirements in Critical Care trial, a restrictive transfusion strategy was associated with improved survival in younger and less severely ill patients. Based on data from retrospective cohort studies of patients who refuse transfusions for religious reasons, we all recognize that there is a point where anemia will definitely increase morbidity and mortality. However, the point at which anemia becomes problematic for a given patient is unknown, as is the point at which transfusions will improve survival. Thus, theoretical arguments based on innumerable retrospective cohort studies have been made either in favour of or against a RBC transfusion, and clinical practice varies accordingly. Given the high degree of uncertainty surrounding the benefits or the risks of transfusions, the decision to transfuse can be relatively difficult in certain cases. When a patient is bleeding during surgery, the hemoglobin (Hb) concentration falls and the patient may require a RBC transfusion depending on his/her physiological condition, the clinical context, and the Hb concentration. However, in the absence of convincing evidence, clinicians tend to rely mainly on the Hb concentration when deciding whether to transfuse patients, irrespective of the patient’s age and physiological (particularly cardiovascular) condition. This oversimplification of a complex situation is probably unavoidable at present, but it underscores the urgent need for trials to test the effects of different transfusion strategies on functional outcomes, morbidity, and mortality in different patient populations. In recent years, only three studies have presented high quality evidence regarding the Hb concentration that should prompt consideration of transfusion, and a fourth should be published soon. The latter study should provide helpful information Dr. Hardy holds the Hema-Quebec Foundation—Bayer Chair of Transfusion Medicine of the University of Montreal.