Objective: To determine the histopathological subtypes of colorectal carcinoma by WHO in 2000 and indentify expression characteristics of some immunohistochemical markers in colorectal arcinomas. Material and method: The paraffin blocks from 157 patients diagnosed and treated at the Hospital K with colorectal cancer were used for the histology and immunohistochemical study at the Center for Research and Early Detection of Cancer. The cases were histologically classified according to the WHO 2000 classification of colorectal tumors. All the cases were stained for CK7, CK19, CK20, CDX2, Her-2/neu, p53 and Ki67 markers by immunohistochemical ABC techniques. Results: Histologically, adenocarcimas were identified in 90.4 percent of cases, mucinous carcinomas in 6.4 percent, signet ring cell carcinomas in 1.9 percent and undifferentiated carcinomas in 1.3 percent. Moderately diffentiated adeocarcinoma percentage was 50.7 percent, low differentited adenocarcinoma was 29.6 percent and highly (well) differentiated adenocarcinoma was 19.7 percent. CK7 is low expressed in the colon carcinomas (10.2 percent), while CK19, CK20 and CDX2 were highly expressed in the colon carcinoma (96.2 percent, 58.6 percent and 754 percent, respectively). Ki-67 was expressed in 66.9 percent, p53 in 43.3 percent and Heff-2/neu in 12.1 percent of cases. Positive rate of Ki-67 increased with the decrease of differentiation level of adenocarciomas. Conclusion: The great majority of colorectal carcinoma were adenocarcinomas, majority of adenocarcinomas were moderately differentiated and CK7(-)/CK19(+), CDX-2(+) phenotype is characteristic of colorectal carcinoma and very helpful in differential diagnosis of colorectal carcinomas from metastatic carcinomas of other organs.