The Venn diagram shows the overlapping features in pediatric¹ and adult² allo-HSCT recipients. In adults, diversity of the pretransplant and peri-engraftment intestinal microbial communities has been associated with overall survival (OS): high diversity correlates with longer OS. In this pediatric study, the diversity of the pretransplant microbiome was correlated with OS, but the peri-engraftment time point was not. The survival curve denotes the common finding between pediatric¹ and adult^2,3 allo-HSCT recipients: ie, higher microbial diversity pretransplant is associated with improved OS. Professional illustration by Patrick Lane, ScEYEnce Studios.