Introduction & Objective: At the present, cancer is the third factor in mortality and constitutes. The second grand of non-transmitted chronic disease. The colorectal cancer is among the most important kind of cancer through out the world. It is the most prevalent cancer of the gastrointestinal system. It constitutes about 70% of the mortality due to cancer. In this project we have made an epidemiologic study of colorectal cancer in Arak for a period of ten years. Materials & Methods: In this descriptive study, the documents of 274 patients with colorectal cancer hospitallized in Vali Asr, Imam Khomeini and Ghods hospital in Arak during 1994-2004 were evaluated. The extracted data consisted of age, sex, stage of disease with, type of cancer, the primary symptom at the time of referring time were analyzed by SPSS software. Results: There were 54.7% men and 45.3% women. The mean age of the patient's age was 56.22 and 17.5 percent of them were less than 40 years old. Most patients were in the third stage of cancer at the diagnosis time and the most prevalent type of the cancer has been adenocarcinoma. The most prevalent region of anatomic lesion was rectum. Rectorrhagia was reported to be the most prevalent symptom at the first referral. Conclusions: Considering the high frequency of the patients with age less than 40 years and the youthfulness of the society genetic problems and environmental risk factors should be considered. Assessment of risk factors and the isolation of patients should be done at the earlier stage. Considering the high frequency of rectosigmoid tumors in our study, it seems that fiberoptic sigmoidoscopy method has important role in the early diagnosis and treatment of these patients in Iran.