Acute lymphoblastic leukemia (ALL) is a relatively rare disease during pregnancy, accounting for about 15% of all cases of pregnancy-associated leukemia. Although mixed lineage leukemia gene (MLL) rearrangement is the dominant genetic aberration in infantile acute leukemia, the occurrence of MLL gene rearrangement in maternal ALL occurring during pregnancy has not been reported. Out of 31 cases of maternal leukemia diagnosed during pregnancy at our institution, 5 were ALL cases. Three of the 5 patients had MLL gene rearrangement. The data for these 5 patients are presented in this report. We believe that the association of MLL gene rearrangement with maternal leukemia is biologically plausible and this observation needs to be validated in a larger cohort of pregnancy-associated maternal leukemia cases.