Intra-abdominal infections (IAIs) include a lot of pathological conditions occurring in the abdomen ranging from uncomplicated appendicitis to faecal peritonitis and represent a daily challenge worldwide. Every physician during his professional life will treat a case of IAIs. Despite of this the treatment of IAIs is still controversial and often involve only one professional figure. WSES (World Society of Emergency Surgery) try to uniform the treatment of IAIs through the publication of the WSES Guidelines. The WSES board involves general surgeons, critical care surgeons, internists, anesthetists, infectious diseases specialists, critical care medicine specialists and other professional figures such as pharmacologists. In order to observe the worldwide state of art of IAIs treatment, WSES started a worldwide observational study (CIAOW Study). Conclusions of CIAOW study are very interesting to find factors affecting mortality in IAIs. There are some factors regarding patients such as clinical conditions at entrance or presence of comorbidities and other factors affecting mortality directly rising from treatment such as immediate source control or adequate antimicrobial therapy.