Histological assessments continue to have an important role in the diagnosis and management of graft complications following liver transplantation. For some conditions, such as liver allograft rejection, histology is regarded as the "gold standard" for diagnosis. In other cases, where a likely cause of graft dysfunction has been identified using other methods, liver biopsy provides important additional information (e.g., severity of necroinflammatory activity and fibrosis in recurrent hepatitis C infection) and may point to the presence of an additional or alternative cause for graft dysfunction. In cases where a dual pathology is suspected (eg, hepatitis C and rejection), histological findings can help to identify the main cause of graft dysfunction. This article will focus on the main patterns of damage that are seen in post-transplant liver biopsies and their differential diagnosis. As with the assessment of liver biopsies in the native liver, clinico-pathological correlation is very important. Consideration should also be given to the therapeutic implications of the biopsy report, in particular whether changes in immunosuppression are indicated.