According to literature data, colorectal cancer may coexist in 0.02-0.1% of all pregnancies. Pregnant women may develop any type of malignancy, usually breast cancer, cervical cancer, lymphomas, malignant melanoma, leukemias, ovarian cancer, thyroid cancer and digestive tract tumors. The commonest digestive tract malignancies are large bowel and rectal cancer. Pregnancy may alter the course of neoplastic disease. In this setting, one of the key diagnostic problems is the masking of tumor signs and symptoms by coexisting pregnancy, making correct diagnosis considerably more difficult. This results in higher clinical stages at presentation and delayed treatment. First published reports of colorectal cancer during pregnancy are usually incidental findings, discovered as a result of treatment of various complications of pregnancy. Modern oncologic science, supported by early tumor detection programs, enables timely diagnosis and effective treatment of many digestive tract tumors. Nevertheless, distortion of tumor signs by pregnancy, different dynamics of tumor growth, pregnancy-imposed limitations of diagnostic and therapeutic modalities, all contribute to delayed diagnosis and institution of correct treatment. Doctors should be vigilant and able to differentiate signs and symptoms pregnancy-related from those indicating a colorectal cancer. The scope of diagnostic and therapeutic modalities implemented when faced with a colorectal cancer coexisting or not with pregnancy is similar. Apart of clinical stage and tumor location, the key factors influencing timing and mode of treatment of a pregnant woman are gestational age and condition of the fetus.