Emergency surgery for colorectal cancer is associated with a higher postoperative morbidity and mortality rate and a poor long-term outcome compared with elective surgery. The aim of the present study was to compare early and late outcome after elective and emergency surgery for malignant colorectal cancer, looking for the principal determinants of a worse outcome after emergency colorectal surgery. A retrospective study of 236 patients presenting with colorectal cancer over an 8-year period was undertaken. Of these, 118 presented as emergencies, whereas 118 patients, well matched for age, sex, site of tumor and TNM admitted as elective, were included in the study. Data reviewed included postoperative mortality and morbidity and long-term outcome. The 30-day operative mortality rate was significantly higher in the emergency group than in the electively treated group (11.9% versus 3.4%, P < 0.01). The higher mortality rate was observed in the perforation group. The 30-day operative morbidity was higher in the emergency group (27.1% versus 12.7%, P < 0.05). Anastomotic failure was a serious complication: following primary resection, we observed 4 non-fatal (5.4%) and two fatal (2.7%) anastomotic leaks after 74 primary anastomoses. Among emergency-treated patients, the procedures characterized by the highest percentage of postoperative complications were three-stage resections (63.6%). The 5-year survival rate was greater after elective surgery (59% versus 39%). The early and long-term outcome following emergency colorectal surgery was significantly lower than that after elective surgery. Although medical complications in patients with end-stage cancer played an important role, surgical failures still had an important impact on outcome.