In primary care, the principal aim should be to identify patients whose bleeding diathesis could be caused by leukaemia, meningococcal septicaemia or other acute systemic disease, severe haemorrhagic disease, medication-induced complication or an assault. The assessment of a patient with a bleeding diathesis differs from the management of a patient with an acute haemorrhage. In addition to clinical examination, the patient's age, sex, underlying diseases, medication, type of bleeding as well as family history, including distant relatives, will provide essential information that is required before additional investigations are ordered. A haemostatic disorder leading to a bleeding diathesis may be acquired or hereditary. In both cases, such a disorder may either be mediated via platelets or coagulation factors. Bleeding diathesis may also be caused by abnormal fibrinolysis or by structural abnormalities in the vessel walls or in connective tissue.