Cost-effectiveness analyses, particularly in the USA, commonly use a figure of $50,000 per life-year or quality-adjusted life-year gained as a threshold for assessing the cost-effectiveness of an intervention. The history of this practice is ill defined, although it has been linked to the end-stage renal disease kidney dialysis cost-effectiveness literature from the 1980s. The use of $50,000 as a benchmark for assessing the cost-effectiveness of an intervention first emerged in 1992 and became widely used after 1996. The appeal of the $50,000 figure appears to lie in the convenience of a round number rather than in the value of renal dialysis. Rather than arbitrary thresholds, estimates of willingness to pay and the opportunity cost of healthcare resources are needed.