Peled JU, Gomes ALC, Devlin SM, et al. - This study sought to assess whether microbiota as a predictor of mortality in allogeneic hematopoietic-cell transplantation. A total of 8,767 fecal samples collected from 1,362 individuals who underwent allogeneic hematopoietic-cell transplantation at the four centers. Relationships were analyzed between microbiota diversity and mortality applying Cox proportional-hazards analysis in an observational study. The median diversity value that was seen at the study center in New York was used for stratification of the cohorts into higher- and lower-diversity groups. During allogeneic hematopoietic-cell transplantation, patterns of microbiota disruption were similar across transplantation centers and geographic locations; patterns were marked by loss of diversity and domination by single taxa. The results of this study demonstrated that higher diversity of intestinal microbiota at the time of neutrophil engraftment was correlated with lower mortality.