Goal of this study was to compare the quantitative coronary arteriographic (QCA) results obtained with the Philips DCI/ACA analytical software package with those from postmortem casts in an animal experimental setting. Standard digital coronary arteriograms were obtained from 6 mongrel dogs. After the imaging procedure, the dogs were sacrificed and casts were made of the coronary trees by filling the vessels with a mixture of radio-opaque barium and silicone gel at a fixed pressure of 100 mmHg. Vessel diameters were measured from the digital arteriograms at a total of 118 selected locations with the ACA package. Thin slices were cut from the casts at these same measurement locations and the areas of the cross sections were obtained by manual tracing of the outline of each slice in an approximately 40 x magnified image. From these cross-sectional areas, cast diameters were derived using the formula for circular cross-sections. Cast diameters ranged in size from 0.69 to 3.30 mm. The systematic error between the measurements was found to be 0.058 mm; (p < 0.015) and the standard deviation of the signed difference 0.255 mm; the correlation coefficient was r = 0.91. The largest error sources are supposed to be the slight differences in the selection of identical positions in the X-ray images and on the casts, and the 'out-of-plane' magnification for a number of vessel locations. This postmortem study demonstrates that the diameters of coronary vessels can be measured from digital arteriograms with the DCI/ACA package with a high degree of accuracy and precision.