Wear particles produced by vibratory cavitation erosion tests on 1017 carbon steels in water and oil-in-water (o∕w) emulsions were analyzed. Scanning electron microscope (SEM) images of wear particles were acquired, forming a database for further analysis. The particle morphology features were first clarified. Next, the size parameters (size, area, and perimeter) and shape factors (elongation and roundness) were determined for each test liquid, using image analysis software. The size parameters of the removed particles were higher in water than in o∕w emulsions. While the shape factors could not significantly discriminate between the particles produced in water and o∕w emulsions. The size distribution was in a wide range for water than that for o∕w emulsions. The cavitation erosion mechanism is fatigue failure for water and o∕w emulsions.