Antibiotics combined with lavage have demonstrated a reduction in the bacterial contamination and decreases SSI infection rate. SSI leads to an immunocompromised situation, as immunologic defense is focused on controlling the septic focus, leaving unattended the neoplasm. It has been described that SSI may result in a worse oncologic outcome. The aim of this study is to evaluate prospectively the effect of peritoneal lavage with clindamycin and gentamicin on the oncologic outcome of colorectal tumours.