The importance of hemodialysis session length relative to small solute (e.g., urea) clearance has been debated for many years. Longer session length augments clearance of larger molecules and may facilitate ultrafiltration; however, the independent effects of session length on survival and other outcomes are unknown. In this report, we review two recently published observational studies examining the association between hemodialysis session length and survival. Prospective clinical trials will be required to resolve the debate.