The registry of digestive tumors of the department of Cote-d'Or recorded between 1976 and 1982, among 1543 colorectal cancers, 142 cases (9.2%) diagnosed with acute obstruction. Distribution of the tumors along the large bowel was as follows: rectal cancers were rarely obstructive (3.8%) whereas it was a more common feature in the sigmoid (14.2%), the caecum (12.2%) and the transverse colon (15.8%). Symptoms preceded the acute obstruction in 39.7% of the cases. Limited tumors were rare in obstructive cancers, 2.8% were Dukes A, 30.3% Dukes B; the corresponding data for non obstructive cancers were 15.6 and 27.7% respectively (P less than 0.01). Treatment was surgical in 97.9% of obstructive cancers. Surgery was more often palliative in obstructive tumors (45.8%) than in the other types of tumors (21.3%; P less than 0.01). The postoperative mortality rate was 30.9%, ie 21.6% after curative surgery, 30% after palliative surgery, 43.6% after derivative surgery. The overall survival rates for obstructive cancers were 42.7% after one year and 17.6% after 5 years; they were respectively 59.1 and 31.1% for non obstructive cancers (P less than 0.001). After curative surgery and excluding postoperative mortality prognosis was the same for obstructive and obstructive cancers within the same Dukes' stage. This study permitted to highlight the rather high frequency of obstructive colorectal cancers, and their bad prognosis linked to the extension of the tumors and to high postoperative mortality rates.