In the orthopantomogram a reproducible determination of the gonial angle is possible. When comparing two orthopantomograms of the same patient, which were taken during routine clinical examination, a variation of the arithmetic mean of the gonial angle by 1 degrees was found. The value of the gonial angle measured in the orthopantomogram is 2.2 degrees to 3.6 degrees smaller than in the lateral cephalometric radiograph. In single cases, however, a wider range occurred. Therefore in determining the gonial angle, the lateral cephalometric radiograph should be preferred.