The prevalence of pregnancy associated leukemia is approximately 1 case out of 10,000 pregnancies. This rare occurrence precludes the conducting of large, prospective studies to examine diagnostic, management and outcome issues. The treatment of a pregnant woman with leukemia may be associated with severe adverse fetal outcome including death and malformations, and therefore poses a difficult challenge for both the patient and the attending physician. Chemotherapy during the 1st trimester is associated with an increased risk for congenital malformations. However, this risk diminishes as pregnancy advances. When acute leukemia is diagnosed during the 1st trimester, patients should be treated promptly similar to non-pregnant patients. However, the aggressive induction therapy should follow pregnancy termination. When the diagnosis is made later in pregnancy standard chemotherapy regimen should be considered and usually pregnancy termination is not mandatory. However, both the mother and the fetus should be under close observation and delivery should be postponed to a non-cytopenic period. Pregnancy associated chronic myelogenous leukemia (CML) can be treated with interferon throughout pregnancy with no apparent increase in adverse fetal outcome. In the very rare case of chronic lymphocytic leukemia (CLL) during pregnancy treatment can usually be delayed until after delivery.