A malignancy discovered in pregnancy is often difficult to manage; the optimal maternal therapy has to be balanced with the fetal well-being. Generally, the cancer is managed as though the patient is not pregnant. For the various site-specific cancers, surgery is the main modality of treatment; this should be individualized. Chemotherapeutic agents are highly teratogenic in the first trimester, with some adverse effects when used after 12 weeks' gestation. The overall survival rate for pregnancy-associated breast cancer is poor; the reasons for this are discussed. For cervical cancer, delivery by caesarean section appears to be the method of choice, with significantly better survival rates compared with those who deliver vaginally. Other gynaecological and non-gynaecological malignancies are discussed.