Immediately after coronarography 10 mCi 133Xenon were injected into the left or right coronary artery. A scintillation camera was placed above the thorax of the patient. A computer unit (KRUPP EPR 2500) with magnetic tapes and discs is available for data processing and data storage. Sequential images of the heart are taken over a period of 2 min in a two-second-frame mode and stored on magnetic tape. The total image was divided into 5 - 5 mm areas. From each area a functional curve was registered and the Myocardial Blood Flow (ml/min/100 g myocard) could be calculated from that. For a precise evaluation of the image of the Myocardial Blood Flow, any influences originating from other regions of the body had to be excluded. Therefore all curves are rejected which did not (a) reach their maximum value within 15s after injection, or (b) where the maximum was less than 10% of the highest maximum value of the reference curve. The values of the Myocardial Blood Flow calculated in this manner are displayed on a TV-screen. These values can be transformed into 10 colors or grey levels. This method has been proven to be useful in clinical practice for functional studies, especially for the judgement of the effectivity of pharmaceuticals. The quantitative display technique of the "Myocardial Blood Flow" improves the clinical statement in comparison to a scintigraphic picture.