Lactococcus garvieae, a Gram-positive lactococcus with a short incubation period and high virulence, is a known fish pathogen responsible for serious outbreaks in both marine and freshwater aquaculture. The first human infection was documented in 1991. This is the first case report of L. garvieae endocarditis in the Netherlands.A 68-year-old woman presented with a three-week history of intermittent fever, increased bleeding tendency and weight loss. Blood tests showed prolonged clotting times and diffuse liver dysfunction. Transoesophageal ultrasound showed a vegetation on the aortic valve. Blood cultures were positive for L. garvieae, leading to a diagnosis of 'infective endocarditis'. Additional examination revealed liver cirrhosis and pandiverticulosis. The patient was treated with intravenous antibiotics for six weeks and made a good recovery.Consumption of raw fish, immunosuppression and an abnormality in the gastrointestinal tract are risk factors for L. garvieae infection. Improved determination techniques are likely to lead to more frequent identification of the bacterium.