In 1963 Jean Bernard introduced the concept of “geographic hematology” and distinguished 2 branches, i.e., “ethnic hematology,” which deals with differences between populations, and “environmental hematology,” which considers factors such as food habits, infections, and others. Both of these branches have implications in the distribution of hematological diseases worldwide. In comparison with Caucasian populations, in Mexico a significantly higher prevalence of acute lymphoblastic, acute promyelocytic, and acute megakaryoblastic leukemias has been described. The rate of chronic myeloid leukemia seems to be as high as that reported in Caucasian populations, while other myeloproliferative neoplasias are significantly less frequent in Mexico. Significantly lower prevalences of hairy cell leukemia, chronic lymphocytic leukemia, multiple myeloma, and Waldenström’s macroglobulinemia have been reported from Mexico. Regrettably, the influence of drug companies interested in selling their new and expensive drugs has resulted in both overdiagnosis of some diseases and overidentification of the refractory forms of some of these conditions to justify the use of unnecessary drugs.