A decision to perform coronary angioplasty on a constricted coronary artery should always be preceded by objective evidence of myocardial ischaemia in the flow region concerned. However, for patients with multi-vessel coronary disease it can be difficult to determine which of the several coronary stenoses present is responsible for the anginal complaints. Recently, special miniaturized sensor-equipped guide wires are introduced in the cardiac catheterisation laboratory. Therefore it is now possible to selectively evaluate coronary stenoses by means of haemodynamic parameters: fractional flow reserve (FFR, based on intracoronary derived pressure measurements) and coronary flow velocity reserve (CFVR, based on intracoronary derived Doppler flow velocity measurements). The diagnosis of coronary artery disease in the cardiac catheterisation laboratory has improved considerably due to the use of these intracoronary derived haemodynamic parameters. Several clinical studies have shown that it is safe to defer a coronary angioplasty based on an FFR > or = 0.75 or a CFVR > or = 2.0. In the case of an abnormal FFR or CFVR result, the appropriate treatment strategy can be implemented. Furthermore, these parameters can be used to evaluate the result of the therapy.