Colonic cancer during pregnancy is rare. Herein we describe a case of adenocarcinoma of the transverse colon in a 29-year-old pregnant patient. Early diagnosis is difficult because the initial symptoms of colorectal cancer, such as abdominal pain, nausea and vomiting, constipation, and abdominal distention, are often attributed to a normal pregnancy. Management of colonic cancer during pregnancy depends on gestational age and operability of the tumor. Medical and surgical management considerations are discussed.