Cancer complicating pregnancy endangers two lives. Any approach should look at both maternal and foetal safety. Maternal prognosis will not improve by terminating the pregnancy. Imaging for staging purposes is possible, and sonar and magnetic resonance imaging are the preferred examinations. Abdominopelvic computed tomography exposes the foetus to the highest doses radiation and should be avoided. Provided a thorough maternal monitoring to ensure a stable uteroplacental blood flow and foetal oxygenation, surgical techniques that are used in non-pregnant patients are also safe for pregnant patients. Radiotherapy of the upper part of the body is possible during pregnancy, but during the third trimester the close distance may put the foetus at risk. Chemotherapy during the second or third trimester can be administered without increasing the incidence of congenital malformations. A systematic analysis, especially on the long-term outcome of the offspring after cancer treatment during pregnancy is still lacking. Here, we present a summary of issues related to the diagnosis and treatment of gynaecological malignancies during pregnancy. Firstly, we describe general diagnostic and cancer-treatment-related problems. In the second part, organ pathology including breast, cervical, ovarian, endometrial and vulvar cancer is discussed.