Hospital readmission rates in complex colorrectal surgery background: non programmed hospital readmission rates are a quality indicator of colorectal surgery. aim: To analyze the causes of readmission of patients subjected to surgical procedures including intestinal anastomoses. material and methods: Analysis of a database of patients subjected to elective intestinal anastomoses in a period of 10 years. All non-programmed readmissions that occurred within 30 days after patient discharge were analyzed. results: Overall non-programmed readmission rate was 7% and it was due to medical causes in 55% of patients. nine percent of readmitted patients required a new surgical intervention. The figure among patients readmitted due to surgical causes, was 20%. Sixty one percent of patients were admitted at less than six days after discharge and 84% at less than 10 days. A non-programmed readmission duplicated the total hospitalization lapse and triplicated the rates of new surgical procedures. conclusions: In this series of patients, the only predictor of a non-programmed readmission was the need for reoperation during the first admission.