Some diseases and drugs have previously been associated with increased risk for colon cancer. A case-control study on colon adenocarcinoma was conducted encompassing 329 cases and 658 controls. History of previous diseases and drug intake was assessed by questionnaire. Appendectomy was associated with a protective effect with odds ratio (OR) 0.5 and 95% confidence interval (CI) 0.2-0.9. Cholecystectomy was associated with increased risk, especially in females, for right sided and transverse colon cancer, OR 1.5 (CI 0.9-2.5) and OR 1.8 (CI 0.8-3.5), respectively. Ulcerative colitis increased the risk, OR 11 (CI 3.5-38). Also hyperplasia of the prostate gland and diabetes in men were related to an increased risk with OR 4.4 (CI 1.5-13) and OR 2.9 (CI 1.4-6.0), respectively. For men and women together diabetes mellitus yielded an increased OR of 1.7 (1.0-3.0). Regarding drugs somewhat increased risks were found for beta-2-stimulating agents, OR 1.9 (CI 0.6-5.4), benzodiazepine, OR 1.7 (CI 0.9-3.3), iron, OR 1.9 (CI 0.5-6.7), and paracetamol, OR 2.5 (0.6-8.5). Increased risks were found for hydralazine in men, OR 2.3 (CI 0.7-7.0), methyldopa in men, OR 4.3 (1.1-18), sulfonylurea, OR 2.9 (CI 1.2-6.7), and verapamil, OR 22 (CI 2.4-480). Somewhat decreased risk was found for indometacin, OR 0.6 (0.2-1.6).