Our objective was to determine the association between the methylenetetrahydrofolate reductase polymorphisms (C677T and A1298C) and the risk of developing acute lymphoblastic leukemia (ALL), chronic myeloid leukemia (CML), acute myeloid leukemia (AML), and multiple myelomas (MM) in Latinos. The gene discussed is MTHFR; the disease is plasma cell myeloma.