We report the case of an HIV-positive man who presented with pyrexia of unknown origin. Histological specimens from an inguinal lymph node and liver biopsy gave a diagnosis of Epstein Barr virus (EBV)-positive Hodgkin's lymphoma and haemophagocytic lymphohistiocytosis (HLH), respectively. HLH is a condition characterized by proliferation of activated macrophages that phagocytose leukocytes, erythrocytes and platelets. Clinical features include splenomegaly, fever and pancytopenia, all of which have a wide differential diagnosis in HIV-positive patients. HLH can be caused by infections, malignancy, drugs or autoimmune conditions. There have been a number of reports of HLH in HIV-positive patients, and it can be seen at all stages of HIV infection. HIV, lymphomas, EBV infection and haemophagocytic syndrome have a complicated pathophysiology. Unfortunately, HLH in this setting has a particularly aggressive course, often with a poor outcome. This case highlights the need for awareness of the syndrome to ensure prompt diagnosis and instigation of appropriate treatment.