Abstract: Processors are washing carcasses with one or more inside-outside bird washers (IOBW) to comply with the zero tolerance for visible feces regulation mandated by the USDA Food Safety Inspection Service. A study was conducted to determine the effect of an IOBW on total aerobic bacteria, E. coli, Campylobacter, and Salmonella recovered from uncontaminated (control), contaminated, and possibly cross contaminated broiler carcasses at two different IOBW water pressure settings. In each of three trials, 12 commercially processed carcasses, divided into two groups each containing two control carcasses, two carcasses contaminated with 0.1g cecal contents (inoculated with Campylobacter and Salmonella), and two carcasses uncontaminated and placed adjacent to contaminated birds during washing (to determine cross contamination) were prepared (n=36). Whole carcass rinses were conducted on carcasses before contamination and washing, then again after washing. Carcasses were washed with an in-line commercial IOBW set at 140 birds per minute for a 5 sec dwell time and either 276 or 552 kPa (40 or 80 PSI) water pressure. Counts of total bacteria, E. coli, Campylobacter, or Salmonella were not significantly affected (P< 0.05) by contamination with feces, by cross-contamination, or by IOBW pressure. The overall effect of washing was a slight but significant reduction in total aerobic bacteria (4.9 to 4.8) and E. coli (3.2 to 3.0) log cfu/ml rinsate. The IOBW decreased the incidence of Campylobacter from 22/36 positive carcasses (14 positive incoming carcasses plus 8 inoculated carcasses) to 1/36 positives, while Salmonella incidence decreased from 12/36 contaminated (inoculated) carcasses to 3/36 positive carcasses after washing. The IOBW removed carcass contamination to levels equivalent with uncontaminated controls without cross contaminating other carcasses. The incidence of Campylobacter was decreased, as was Salmonella to a lesser extent. Small reductions of bacterial numbers were noted for total bacteria and E. coli.