To evaluate the cost-effectiveness of screening children born at extremely low birth weight (ELBW) for hepatoblastoma using serial serum alpha-fetoprotein measurements. We created a decision tree to evaluate the cost effectiveness of screening children born at ELBW between 3 and 48 months of age compared with current standard of care (no screening). Our model used discounted lifetime costs and monetary benefits in 2018 US dollars, based on estimates in the published literature. The effects of uncertainty in model parameters were also assessed using univariate sensitivity analyses, in which we changed the values for one parameter at a time to assess the effect on the estimated incremental cost-effectiveness ratio. For the estimated 55 699 children born at ELBW in the US each year, this screening is associated with 77.7 additional quality-adjusted life-years (QALYs) at a cost of $8.7 million. This results in an incremental cost-effectiveness ratio of about $112 000/QALY, which is considered cost effective from a US societal perspective. For children diagnosed with hepatoblastoma, our model finds that the screening regimen is associated with a 10.1% increase in survival, a 4.18% increase in expected QALYs, and a $245 184 decrease in expected cost. Screening ELBW children for hepatoblastoma between 3 and 48 months of age dominates the alternative and is cost effective from a societal perspective. Copyright © 2020 Elsevier Inc. All rights reserved.