Background: Diverting loop ileostomy (LI) is commonly performed to protect a distal anastomosis after a low anterior resection. Aim: To investigate the frecuency and clinical features of ileostomic dysfunction (ID) and, eventually, to define a profile of patients at risk of this complicaction. Materials and Method: 103 consecutive patients operated on for rectal cancer were included. ID is defined when the maxime output was more than 1,5 lt/day for three or more consecutive days with biochemical disturbances, associated to abdominal distension and the inability to tolerate oral feeding without postoperative severe complication. Patients with ID were compared with noID group. Results: ID developed in 15 patients, lasting between 12 and 70 days (50% for more then 30 days), the readmission rate was 27% without reoperation in this group. Except for inhospital time and readmission rate, no other difference between both groups were founded. Discussion: ID is a kind of paralitic ileus of variable intensity with paradox high output ileostomy leading to depletion of water and electrolyte imbalance. ID requires reposition of high volumen of fluids and electrolytes and sometimes parenteral nutrition with full recovery in variable periods without invasive treatment. In this study it was not possible to define a patient profile at risk or predictive factores of this complication.