An early determination of pulpal vitality is crucial with respect to a correct differential diagnosis of revascularisation or necrosis and its treatment.Sensibility tests (cold, heat, electrical pulp test) in combination with radiographs are commonly promoted. However these tests are arbitrary, based on sensations and therefore not always reliable. In such situations registration of pulpal blood flow will be advantageous. The most studied and well documented method for registration of blood circulation is laser Doppler flowmetry (LDF) which is typified as a non-invasive technique with direct and objective registrations. In this article blood flow, LDF and its characteristics, the advantages and disadvantages of the methods and the latest developments regarding LDF is described.Despite there being a low implementation of LDF in dentistry to date, this should become one of the basic techniques for clinical use in paediatric dentistry.