The lack of quantitative information about the properties of the tissue interface is one shortcoming in imaging biological structures with the echo-ranging ultrasonic technique. A multitransducer configuration offers a method for experimentally evaluating a reflection coefficient for arbitrarily oriented interfaces. Mathematical analysis indicates that this is feasible. Experiments with interfaces formed by water and aluminium, and acrylic plastics and polyethylene have demonstrated accuracies of 20% for orientations ranging between ±1 degree from the normal.