It is common practice to soak acute traumatic wounds in dilute povidoneiodine solution before definitive wound cleaning and debridement. The effectiveness of soaking wounds is unknown. Using quantitative wound bacterial counts as a measure of efficacy, we compared wounds soaked in 1% povidone-iodine solution or in normal saline with wounds receiving no treatment. Adult patients were eligible for the study if they were seen in the emergency department with visibly contaminated traumatic wounds w~thin 12 hours of injury, Patients were excluded if they refused consent, were allergic to iodine, or had taken antibiotics within five days; if the wound did not require debridement; if the wound had been previously cleaned; or if subsequent cultures were sterile. Thirty-three heavily contaminated acute traumatic wounds in 29 patients were included in the study, Wounds were randomly assigned to one of three groups. Tissue samples were taken before and after a ten-minute period of soaking in either povidone-iodine or saline; controls were covered with gauze during the ten-minute period. The mean bacterial count per gram of tissue decreased 6.4 x l0 s (standard deviation, 1.68 x 104) after no soak, increased 3.39 x 107 (1.05 x 108) after saline soak, and decreased 9.•9 x 106 (1.72 x 107) after povidone-iodine soak. Wounds with counts of less than l0 s bacteria/ g tissue are unlikely to become infected. Multiple regression analysis was used to analyze the changes in bacterial count after treatment as a function of experimental group and initial bacterial count. There was no significant difference between the control and povidone-iodine groups. However, the saline group had a significant trend toward increased bacterial counts after treatment (P = .000I). We conclude that soaking heavily contaminated acute traumatic wounds in 1% povidone-iodine solution for ten minutes does not decrease bacterial counts, and soaking in saline before cleaning and debridement increases bacterial counts. Soaking wounds in povidone-iodine solution is not an effective substitute for the usual techniques of wound cleaning.