OBJECTIVE: To highlight the issue of diagnostics and treatment management in colorectal cancer of pregnant women. DESIGN: Case report. SETTING: Department of Obstetrics and Gynaecology, Pardubice Hospital. CASE REPORT: We present a case of a 24-year-old secundigravida, diagnosed as colorectal cancer in week 34 of pregnancy, manifesting as a diarrhoea and a stomach ache. The diagnosis was made in an advanced stage due to underestimation of clinical symptoms. CONCLUSION: The diagnosis of the colorectal cancer in pregnancy can be difficult because the presenting symptoms are easily attributable to pregnancy. Therefore the advanced disease is diagnosed more frequently in pregnant patients than in the general population. Colorectal cancer should be managed by multidisciplinary team with regard to gestation.