Females have an increased capacity to recover from ischaemia–reperfusion injury (IRI) compared to males, according to new research. Female mice deficient in the estrogen receptor displayed exacerbated renal IRI, but mice that received supplemental estrogen were protected. This sex-specific difference was also implied from analysis of data from the United Network for Organ Sharing database, which indicated a greater association with delayed graft function in males compared to females. The researchers propose that estrogen might have therapeutic potential to improve IRI tolerance.