Current prevention, diagnostic management and therapeutic management strategies for venous thromboembolism (VTE) almost all include an assessment of the clinical probability. Clinical decision rules (CDRs) are decision making tools using combinations of simple available clinical predictors to define a probability of an outcome which can be used in a preventative strategy, diagnostic course of action or therapeutic course of action. CDRs provide accurate and reproducible estimates of clinical outcomes. The best performing CDRs are built and validated following strict methodological standards. In this paper we critically review the use of CDRs in prevention, diagnosis and treatment of VTE and highlight those CDRs that are ready for the prime time of daily clinical use.