The Colorectal Cancer Registry of Modena recorded 838 malignancies of the large bowel between 1984 and 1989. Crude Incidence rates were 59.5 new cases per 100,000 per year in men and 47.4 in women (age-standardised values 33.1 and 20.6, respectively). 35 incident cases (4.2%) had multiple colorectal tumours, whereas 42 (5.1%) had extraintestinal malignancies (mainly breast, endometrium and stomach). Although 90.5% of the patients underwent surgery, this was "curative" in 634 (77.6% of the total), while 105 individuals (12.8%) had palliative operations; 78 patients (9.5%) were not operated, mainly because of metastatic disease or poor clinical condition. Finally, emergency operations--due to intestinal obstruction, perforation or massive bleeding--were carried out in 46 patients (6.1%). A total of 659 tumours (79%) were accurately staged. Among first-degree relatives of the registered patients a significant excess of cases of colorectal cancer was found in each year of the study. 5-year survival was evaluated in 132 (out of 140) patients registered in 1984 and followed-up until 1989. Overall 5-year survival was 37%, but rose to 43% when only colorectal cancer related deaths were taken into consideration. As expected, survival was strongly influenced by stage (P < 0.0001 by log-rank test). In conclusion, this study confirms previously reported data about incidence and mortality rates for colorectal cancer in northern Italy. The particular approach--limited to the large bowel--allowed the evaluation of the frequency of multiple tumours and of the marked aggregation of cancer among first-degree relatives. Finally, survival figures are comparable to those of many other studies and confirm that the clinical outcome of this neoplasm remains unfavourable in more than 50% of the affected patients.