Every year in the UK, around 10 000 children need to have operations to mend injuries to the bed of their fingernails. Currently, most children have their fingernail placed back on the injured nail bed after the operation. The NINJA trial found that children were slightly less likely to have an infection if the nail was thrown away rather than being put back, but the difference between groups was small and could have be due to chance. This study looked at whether replacing the nail is cost-effective compared with throwing it away. Using data from the NINJA trial, we compared costs, healthcare use, and quality of life and assessed the cost-effectiveness of replacing the nail. It was found that throwing the nail away after surgery would save the National Health Service (NHS) £75 (€85) per operation compared with placing the nail back on the nail bed. Changing clinical practice could save the NHS in England £720 000 (€819 000) per year.