The medical literature abounds with risk scores that can help clinicians predict the probability of disease. Risk scores are popular and attractive because they synthesize the effects of several different risk factors for disease in a way that is otherwise too complex for the human mind alone to analyze. However, to optimize clinical decision making, users of risk scores need to consider the factors and methods used to create the score and to recognize the potential limitations of risk scores. Clinicians should consider the patient populations in which the risk score has been developed and validated, the risk factors included in the score, how computing the score might fit into the flow of daily practice, and how risk scores can help estimate pretest probability. An awareness of the uses and potential limitations of using risk assessment tools will aid the clinician in daily clinical decision making. These tools may grow in importance and use with increasing utilization of electronic health records.