The aim of this PhD dissertation was to examine the association between diagnostic delay and stage for colorectal cancer, to determine the extent to which this diagnostic delay for colon cancer patients and/or for rectal cancer patients was caused by patients, general practitioners, or hospitals. We examined the adherence to the Danish Health Authorities guidelines recommending that patients with suspected colorectal cancer be further examined within 14 days, and those with the confirmed diagnosis, be treated within 14 days of diagnosis. Further, we examined the association between symptoms and diagnostic delay and between symptoms and stage. Finally, we sent questionnaires to 20% of the patients' general practitioner to estimate, if the patients and the general practitioners gave the same information about diagnostic delay. The thesis was based on a populationbased observational study from three counties in Denmark, representative of the Danish population. Data of diagnostic delay and symptoms were based on interviews with the patients. A total of 951 patients had primary colorectal cancer, histologically verified as adenocarcinoma, 743 (78.1%) were interviewed, 61 (6.4%) gave no concent, and 147 (15.5%) were excluced because of death, dementia/unable to cooperate, HNPCC, FAP, AFAP, chronic inflammatory bowel disease, or inability to understand Danish. We calculated the relative risk of having an advanced stage (Dukes' C or D) for median delay (61-150 days), and long delay (150 days) with short delay (