Steatosis or fatty change is a common finding in donor liver biopsies during liver transplantation, and seems to be more frequent than in the general population. Fat can be stored in hepatocytes within macrovacuoles (macrosteatosis) or microvacuoles (microsteatosis), with different degrees of severity. Higher degrees of both macro and microsteatosis may increase the severity of the ischemia-reperfusion lesion producing an initial poor function in the recipient. Different pathogenic mechanisms have been investigated. However, only severe macrosteatotic (> 60%) grafts have been associated with primary non-function, and are universally rejected for transplantation. While donor livers with any severity of microsteatosis do not influence recipient survival and can be safely implanted, donor livers with moderate to severe macrosteatosis (30-60%) have a relative risk of primary non-function and should be considered for transplantation in the absence of other known risk factors. A protocol with a rational use of these steatotic livers is suggested.