Background: The treatment-related decision-making process is a highly emotional time for parents of children with incurable cancer, and they tend to continue the cancer-directed treatment even when they realize that there is no cure for their child. Objective: To evaluate whether parents involved in different treatment decisions regretted their treatment decision after their child's death. Methods: We collected prospective data from 418 parents of children who died of incurable cancer after receiving cancer care at 1 of 4 hospitals.