Eighteen digital subtraction angiography (DSA) examinations were retrospectively evaluated for factors that led to their erroneous interpretation. Overlapping vessels obscured pathologic conditions in five cases. In four cases the lesions were not adequately profiled by the DSA projections. Eight lesions were rendered inconspicuous by misregistration artifacts attributable to motion, either from swallowing or from pulsation of vessel walls. One diagnostic error was caused by poor opacification from a degraded contrast bolus secondary to low cardiac output.