A broad spectrum of global haemostatic assays has recently been developed and modified in an attempt to overcome the drawbacks of classical screening tests used for evaluation of coagulation and fibrinolysis. The Overall Haemostasis Potential (OHP) assay is one of such assays. The assay is based on repeated spectrophotometric registration of fibrin-aggregation in citrated plasma, to which small amounts of exogenous thrombin, tissue type plasminogen activator and calcium chloride have been added. The area under the fibrin aggregation curve which then develops is calculated and is the laboratory parameter used for OHP determination. The Overall Coagulation Potential (OCP) and Overall Fibrinolytic Potential (OFP) are supplementary parameters of OHP, providing details of underlying changes in coagulation and/or fibrinolysis. The sensitivity of the assay for detecting hypercoagulation in normal pregnancy, in preeclampsia, some thrombophilias, coronary heart disease, diabetes, stroke and vascular surgery has been evaluated. Since the assay can monitor haemostasis balance in the sample, it may serve as a laboratory tool to determine hypocoagulation, especially in patients with haemophilia A or B. Preliminary findings also indicate that the OHP assay may be useful in the monitoring of anticoagulant treatments. Larger controlled clinical studies are, however, mandatory before a definite conclusion about the usefulness of the method can be drawn.