Thorough irrigation of contaminated or infected traumatic and open surgical wounds is considered standard practice. High-power pulse lavage is frequently used to facilitate the removal of surface contaminants and bacteria but studies to compare the results of various irrigation techniques are limited. The purpose of this randomized, controlled clinical study was to compare the ability of a high-pressure parallel waterjet (pressure range 5,025 to 7,360 psi) to pulse lavage (pressure 40 psi) in reducing wound bacterial counts. The higher velocity instrument utilizes a waterjet oriented parallel to the surface of the wound and can be used to cut and remove necrotic tissues. After obtaining informed consent, 21 patients who presented with open surgical and traumatic wounds were randomly assigned to high-pressure parallel waterjet (n = 12) or pulse lavage (n = 9). Pre- and post irrigation tissue culture results showed an average decrease in absolute bacterial counts of 90.8% in the high-pressure parallel waterjet and 86.9% in the pulse lavage group. The difference between the two treatment groups was not statistically significant. The results of this study confirm that cleansing contaminated or infected acute wounds using high pressure (at least 15 psi) reduces wound bacterial counts. Studies to compare the clinical outcomes of various irrigation techniques and pressure ranges are warranted and the potential benefit of selective debridement using the high-pressure parallel waterjet should be investigated.