Cancer is the second leading cause of death during the reproductive years complicating between 0.02% and 0.1% of pregnancies. This incidence is expected to rise with the increase in age of childbearing. The relatively rare occurrence of pregnancy-associated cancer precludes conducting large, prospective studies to examine diagnostic, management and outcome issues. This article reviews the available data regarding the different aspects of the diagnosis and treatment of cancer during pregnancy as well as the effect of pregnancy on cancer prognosis. In pregnant patients diagnosed with cancer during the first trimester, treatment with multi-drug anti-cancer chemotherapy or radiotherapy (with fetal exposure >0.1-0.2 Gy) is associated with an increased risk of congenital malformations and therefore should follow a strong recommendation for pregnancy termination. The risk for malformation diminishes as pregnancy advances and when cancer is diagnosed during the second or third trimesters there is usually no clear indication for abortion. Treatment postponement, until achieving fetal maturity, while closely monitoring tumor growth may be considered in selected cases. According to the available experience it seems that non-obstetrical surgery may be performed during pregnancy without an increased risk for adverse outcomes. In most types of cancer, pregnancy has no effect on maternal prognosis when compared to non-pregnant patients matched by age, cancer stage and treatment.