OBJECTIVE This study was designed to determine whether pretreatment with an endotoxin antibody reduces tubal damage and tumor necrosis factor-alpha production in an Escherichia coli rabbit salpingitis model. STUDY DESIGN Twenty New Zealand White rabbits underwent laparotomy with direct inoculation of Escherichia coli into the fallopian tube. The animals were given either antibody and antibiotic, antibiotic alone, or no treatment. At 7 days the degree of tubal damage was measured by gross observation, light microscopy, and electron microscopy. Serum tumor necrosis factor-alpha levels were also assayed at 0, 2, 4, and 36 hours. RESULTS Animals pretreated with antiendotoxin antibody demonstrated significantly less damage on the basis of gross observation and electron microscopy compared with both antibiotic alone and untreated animals. Tumor necrosis factor-alpha levels were also significantly reduced at 2 and 4 hours in the antibody-treated group. CONCLUSIONS Endotoxin plays a direct role in tubal damage in this Escherichia coli salpingitis model, and damage can be blocked, in part, by pretreatment with antiendotoxin antibody. Tumor necrosis factor-alpha appears to play a significant role in mediating tubal damage resulting from endotoxin.