We reviewed several cost-effectiveness analyses that modelled the costs and yield of newborn screening for sickle cell disease (SCD) in the US and the UK and discuss the ways in which newborn screening policies in each country evolved with regard to the results of the analyses. Each of the reviewed studies compared the projected cost of universal screening with that of selective screening of children from specific ethnic groups. Despite variability in assumptions, the studies concurred that universal screening in areas with low SCD prevalence would result in a higher cost per case detected, compared with selective screening of children in high-risk ethnic groups. Investigators expressed differing opinions about the economic justification of universal screening, which reflected differences in the understanding of cost effectiveness and in how study questions were framed. Ultimately, policy makers in both countries decided in favour of universal screening, which appears to reflect a growing consensus that ethnically targeted newborn screening is not an acceptable public health strategy. One way to interpret this outcome is that considerations of equity and logistics, including potential stigmatisation, missed cases, and the perceived difficulty and discomfort in ascertaining ethnicity or in separating specimens, trumped economic calculations regarding the relative efficiency of targeted screening. It is not the case that policy makers explicitly favoured equity over economic optimisation; rather, they appear to have given more credence and value to the expert opinion of screening specialists than to the results of economic analyses.