The 1989 Morbidity, Mortality, and Prescription of Dialysis Symposium (Dallas, TX) deeply modified the way of prescribing and delivering hemodialysis (HD) in the United States, as elsewhere. Among strategies emerging for end-stage renal disease treatment improvement, increasing the delivered dose has been the central issue, whereas the session time effect has remained an unsettled question. The purpose of this article is to analyze the trends in HD session time over the last decade in Tassin, France, and elsewhere and their relationship to outcome, independent of dialysis dose. The published data indicate that in the United States, there has been an increase in session time. Outside the United States, where session time had been somewhat longer, there has been either no change or a decrease in time without apparent ill effects. The dialysis dose, as measured by the urea Kt/V, has increased everywhere because improved technology allows for efficient toxin removal within a very short dialysis session. In Tassin, a recent limited experience of high-dose shortened dialysis did not show a significant short-term survival difference, but an impaired control of blood pressure (BP) and nutrition. Thus far, the highest HD long-term survival rates have been reported by the groups that used the largest doses and the longer times of HD. Effects of dose and time are, at this point, impossible to disentangle. A longer dialysis time improves extracellular volume (ECV) and BP control and decreases cardiovascular mortality. Shortening the HD session leads to impaired control of BP and increasing cardiovascular morbidity (by far the first cause of mortality on HD). In the future, the length of dialysis session should be governed by the demand of BP control.