In population based from four Italian cancer registries (Varese, Modena, Latina, Ragusa), five-years relative survival was 34% for colon cancer patients (no. = 1864) and 28% from rectum cancer patients (no. = 1117). However, rectum cancer patients showed higher survival rates in the first year of follow-up, which is possibly due to earlier diagnosis for sites more accessible to clinical examination. For colorectal cancer, age was an important prognostic factor, both in univariate and in multivariate analysis, adjusting for competitive mortality, sex, geographical area and year of diagnosis. In the same multivariate analysis, the prognosis was better for women, significantly for colon cancer and the excess death risk was reduced by 25-30% from 1978-79 to 1984-85. No significant differences were found among different geographical areas, possibly because of the low number of patients from some of the participating cancer registries.