This paper provides biological illustrations of the applicability and mode of use of intravascular and perivascular absolute induction angiometers. Artifacts and limitations of the method as well as experimental precautions and calibration procedures are discussed. Tracings are presented to illustrate the capabilities of the method in recording pulsatile diameter changes in veins and arteries and to demonstrate its applicability to moving blood vessels as exemplified by the coronary arteries. Both intravascular and perivascular angiometry can detect diameter changes of a few micra in a vessel 1 cm in diameter. The inctravascular angiometer is a resilient loop of fine bifilar wire which can be introduced into a blood vessel percutaneously via an angiographic catheter. A perivascular angiometer is an easily deformable loop made of a soft fine wire pair which is draped around a blood vessel and can thus be chronically implanted.