Haematological involvement is common in systemic lupus erythematosus (SLE). Whilst anaemia is most often due to chronic disease, other causes such as autoimmune haemolytic anaemia and hypoplastic anaemia need to be considered. The increased risk of infection in patients with SLE is due in part to changes in the white blood cells though treatments do not yet aim to modify these. Thrombocytopenia occurs frequently and is almost invariably autoimmune. It is often of little consequence, but may occasionally be severe and serious, requiring aggressive treatment. Patients with SLE have an increased risk of thrombosis, increased further in the presence of antiphospholipid antibodies (aPL). Changes in the haemostatic system and new insights into the nature of aPL are described.