The role of health practitioners is no more restricted to the treatment of already established diseases but involves  screening for early detection of asypmtomatic patients, as well as, identification of risk factors that puts an individual at higher risk of developing a disease. Although screening is nowadays considered routine in medical practice, yet its concept is not as straight forward as it appears. Thus, this lecture aims to help health practitioners in applying screening programs for appropriate health-related events and  judging their benefit.