There has been a rapid increase in the use of cost-effectiveness analysis, with quality adjusted life years (QALYs) as an outcome measure, in evaluating both medical technologies and public health interventions. Alongside, there is a growing literature on the monetary value of a QALY based on estimates of the willingness to pay (WTP). This paper conducts a review of the literature on the WTP for a QALY. In total, 24 studies containing 383 unique estimates of the WTP for a QALY are identified. Trimmed mean and median estimates amount to 74,159 and 24,226 Euros (2010 price level), respectively. In regression analyses, the results indicate that the WTP for a QALY is significantly higher if the QALY gain comes from life extension rather than quality of life improvements. The results also show that the WTP for a QALY is dependent on the size of the QALY gain valued.