Although pulsatile flow has been used during cardiopulmonary bypass (CPB) since the early 1950s, the controversy over the benefits of pulsatile perfusion continues. The objective of this study is to investigate whether or not pulsatile flow has any benefit on vital organ recovery compared to conventional non-pulsatile perfusion in pediatric and adult cardiac patients, and to clarify reasons for the controversy in the literature between 1953 and 2003. After reviewing most of the publications in the literature on perfusion modes, the following are the major reasons for the controversy on this issue: a) Lack of a precise quantification of pressure-flow waveforms (Shepard, 1969), b) Poor choice of extracorporeal-circuit components such as pumps and membrane oxygenators, (Undar, 1996), and c) Limitations of experimental designs such as duration of support and patient selection (Undar,2003). The literature suggests that pulsatile perfusion is more beneficial than non-pulsatile perfusion if an adequate pulsatility is achieved. Non-pulsatile perfusion results in capillary collapse and microcirculatory shunting (Mandelbaum, 1956; Tadeka, 1960), increased on the table deaths in 1,217 patients (Taylor, 1986), worsened in postoperative recovery in 259 pediatric patients (Yasui, 1989), increased major complications in 316 adult patients (Murkin, 1995), an increase of endothelial damage and cytokine activation (Orime, 1999), and more activation in complements and neutrophils (Ozatik, 2002). The literature clearly suggests that pulsatile flow is associated with significantly less major complications and deaths after CPB in pediatric and adult patients compared to non-pulsatile perfusion during the past 50 years.