In obstetric patients transfusion is a common procedure, it has many advantages but it also has severe risks. Since the observation that human immunodeficiency virus (HIV) infection is transmitted by transfusion, the number of preventive measures to reduce the infectious diseases transmission by this procedure has increased. The microorganisms that can be transmitted through transfusion include: human T lymphotropic virus (HTLV) I and II, hepatitis B virus, hepatitis C virus, hepatitis D virus, hepatitis G virus, HIV, cytomegalovirus, Treponema pallidum, Barucella sp, Toxoplasma gondii, Plasmodium sp, and Trypanosoma cruzi. The most important measure for reduce transfusion risks is the appropriate and careful use of this procedure. This article review transfusion's indication, describe the infectious diseases commonest transmitted by transfusion and analyze the preventive measures to put in practice.