Background: Since 2002, the worldwide Study for Monitoring Antimicrobial Resistance Trends (SMART) has tracked resistance patterns among aerobic and facultative gram-negative bacilli isolated from patients with intra-abdominal infections. Escherichia coli has been by far the most frequently isolated species. Methods: Antimicrobial susceptibilities for consecutive non-duplicate isolates of aerobic and facultative gram-negative bacilli recovered from intra-abdominal infections were determined by standard broth microdilution techniques. A subanalysis was performed for E. coli isolates from the first three years of the study. Results: A total of 7,002 E. coli isolates were recovered, most commonly from the peritoneal cavity followed by the biliary tract. Susceptibility rates to the 12 antimicrobial agents tested differed among geographic regions, with isolates from Asia/Pacific generally having the high-est resistance rates. Overall, extended-spectrum beta-lactamase (ESBL)-producers had a more antibiotic-resistant profile than non-ESBL-producers but usually were susceptible to the carbapenems and amikacin. Community-acquired E. coli strains comprised slightly more than one-half of the isolates and were susceptible to the agents tested more frequently than were hospital-acquired E. coli. Conclusions: The prevalence of antimicrobial resistance among E. coli isolated from intraabdominal infections is not inconsequential, especially in the Asia/Pacific region. The carbapenems and amikacin were consistently active in vitro against E. coli isolates worldwide, including ESBL-producers.