The development of colon carcinoma during pregnancy is a rare event. However, when colon carcinoma develops during pregnancy it is considered a lethal coincidence due to rapid progression. We report two rare cases of colon adenocarcinoma diagnosed during gestation. Both tumors displayed increased nuclear immunostaining for p53. The increased expression of p53 in tumor cells could indicate that the p53 gene is either mutated or stabilized or alternatively overexpressed as a responses to DNA damage. It is hypothesized that the development of colon carcinoma during pregnancy can be attributed to alterations of the p53 tumor suppressor gene or gene product on one hand and a maternal immune-tolerant state on the other.