The effects of nozzle defects on the behavior of drops ejected from drop-on-demand printheads were studied. Nozzles in two types of commercial printheads were modified with two different micromachining techniques: focused ion beam (FIB) milling and pulsed laser micromachining. Nozzles were modified by producing single or multiple notches on their edges. The studies focused on the volume, speed, and direction of travel of the drops. Fifteen different types of geometrical defects on nozzles were studied. Shadowgraph images were used to determine the drop size, speed, and trajectory from the same nozzles before and after modification. The results indicate that geometrical defects up to ∼100 μm² at the front (exit) face of a 50 μm diameter tapered nozzle do not cause any significant variation in the behavior of these nozzles, but that defects at the back (entry) of the nozzle can have a major effect on the direction of jetting.