The presence of primary or secondary pulmonary hypertension is associated with poor prognosis. Therefore, early diagnosis of this affection is necessary and explains the rapid development of many non-invasive techniques in recent years. Unfortunately, none of these techniques seems to be sensitive and specific enough for the early detection and follow-up of pulmonary hypertension. The development of new non-invasive techniques, such as those associating echocardiography and Doppler effect, and certain radionuclide techniques, may in future allow better non-invasive quantification of pulmonary hypertension. However, these techniques will have to be prospectively tested in patients with pulmonary hypertension of varying origin to determine their clinical value.