ObjectivesTo report clinical features, gross post mortem and histopathological findings from an investigation into sudden or unexpected death in rabbits that was undertaken during an outbreak of rabbit haemorrhagic disease.Materials and MethodsUsing a standard protocol, veterinarians were invited to submit case histories and results of their post mortem examination of pet rabbits that died unexpectedly. Histopathological examination of heart, lungs, liver, spleen and kidney samples was collated with macroscopic appearance and clinical details.ResultsHepatocellular necrosis, characteristic of rabbit haemorrhagic disease, was observed in 185 of 300 (62%) submissions, often accompanied by glomerular thrombosis and changes in other organs. Evidence of rabbit haemorrhagic disease was not apparent on histopathology in 113 of 300 (38%) rabbits. Gross post mortem examination by veterinary practitioners did not always reflect reported histopathological changes. No macroscopic abnormalities were seen in 78/185 (42%) of rabbit haemorrhagic disease cases. Rapid death and death of other rabbits in the household were common features of rabbit haemorrhagic disease. Ante mortem clinical signs included anorexia, collapse, lethargy, seizures, icterus, bleeding from the mouth, dyspnoea, hypothermia, pyrexia, bradycardia or poor blood clotting.Clinical ImportanceRabbit haemorrhagic disease can be suspected from a history of sudden death, especially if multiple rabbits are affected. There is not always macroscopic evidence of the disease but histopathology is useful to support or refute a diagnosis of rabbit haemorrhagic disease and provide information about other causes of death.