Percutaneous coronary intervention (PCI) has become a mainstay in the treatment of patients with coronary artery disease in recent years. Although increasingly complex lesions and higher-risk patients are being successfully treated, restenosis, incomplete revascularization and progression of disease continue to cause a need for a clinical functional assessment, in order to reduce morbidity. Angiographic systematic follow-up, although traditionally considered the gold standard for restenosis and disease progression, should nowadays be considered a valuable approach only to monitor small groups of very high-risk patients. Recurrence of symptoms itself has low sensitivity and specificity in detecting restenosis and myocardial ischemia. Exercise testing may provide useful information on symptoms and functional capacity of the patient; however, it has a low diagnostic power for restenosis and myocardial ischemia with a low sensitivity and specificity. Conversely, the significantly increased sensitivity and specificity obtained by stress nuclear or echocardiographic imaging provide great advantage for the clinical assessment of these patients. Additional advantages of stress imaging are the ability to assess location and extent of myocardial ischemia regardless of symptoms as well as to evaluate patients who are unable to exercise or who have an uninterpretable electrocardiogram. Furthermore, the clear superiority of stress imaging with regard to specificity and predictive value for post-revascularization events makes this functional approach of paramount importance for assessing prognosis of such patients. However, as predictive values of functional stress tests are highly dependent on the pre-test probability of disease, follow-up following PCI should always take into consideration the clinical characteristics of the patient (such as diabetes and age), the angiographic characteristics (severity of disease, myocardium at risk, left ventricular function), the procedural characteristics (length of the lesion, vessel size, number of stents implanted, etc.), symptoms and physical activity of the patient. All these parameters together will assess the risk of the patient and will help to choose a functional appropriate follow-up protocol.