Irrigation of wounds to remove bacteria and foreign material is an essential of wound management along with debridement. The effectiveness of saline lavage by high pressure (50 psi) pulsatile jet irrigation has been compared with conventional gravity flow and bulb syringe procedures. Experimental paravertebral incisional surface wounds in 234 randomized rats were either clean or traumatized and soiled. Wounds in 200 of the rats were seeded with E. coli (log 8.80). Swab specimens of each wound were taken at incision, after seeding, after irrigation, and at three, seven, and ten days after closure. Eulates of more than 1600 specimens were cultured. No anaerobes were found. Irrigation diminished bacterial counts in all wounds, but only pulsatile jet irrigation brought about significant (P less than 0.05) reduction of bacteria in each type of wound. After three days E. coli was significantly diminished in all wounds, regardless of irrigation or none, owing to host defense mechanisms. Nevertheless, clean contaminated wounds were infected at three days but not at seven days after lavage, while traumatized wounds remained infected at ten days except for those initially irrigated by pulsatile jet. Thus, pulsatile jet irrigation removed bacterial from experimental wounds more efficiently than conventional procedures.