OBJECTIVE: To define factors that predict mortality and survival in patients with colorectal cancer who are aged 75 or over. DESIGN: Retrospective study. SETTING: University hospital, Finland. SUBJECTS: 231 patients aged 75 or over who were admitted to hospital with colorectal cancer during the 14-year period 1980-93. MAIN OUTCOME MEASURES: Morbidity, mortality, recurrence, and survival. RESULTS: In-hospital mortality after any kind of operation was 8/211 (4%), and 8/175 (5%) of those who had their tumours resected. Morbidity was 35/175 (20%). Factors associated with mortality were weight loss, Dukes'stage, extent of resection, and type of operation. Overall 5-year survival was 28%, overall 10-year survival was 4%, and median survival was 33 months (range 0-150). Survival was most closely related to Duke's stage, extent of resection, and recurrent disease on univariate analysis, but multivariate analysis identified only mode of recurrence (p