Symptoms and clinical signs suggestive of deep venous thrombosis (DVT) are common and have numerous possible causes. Studies have shown that symptoms and clinical signs in themselves are inaccurate for the diagnosis of DVT. However, clinicians have other information at hand, such as data on risk factors for DVT, that may help improve their ability to predict a diagnosis of DVT in the individual patient. Epidemiological data on DVT incidence and risk factors were reviewed, as were published data on the accuracy of clinical diagnosis of DVT, with the use of both symptoms and signs in isolation and symptoms and signs combined with other clinical information in the form of clinical prediction indexes. Symptoms and clinical signs, when combined with other patient information such as the presence or absence of known risk factors for DVT, can improve clinical prediction considerably. Further study is needed to determine whether clinical prediction indexes have a role in improving the diagnostic process in patients with suspected DVT.