Background　Since 2010, series of cases about acute hypotension related to autologous blood transfusion (AHABT) in cesarean section have been reported, drawing attention from the anesthesiologists　Objective　To reveal the possible mechanisms underlying AHABT in cesarean section.　Content　AHABT may be associated with alterations in several molecules importantly regulating blood pressure during autologous blood transfusion(ABT). First, bradykinin, a vasoactive peptide, accumulates in some patients having lower levels of its degrading enzyme, angiotensin converting enzyme(ACE). ABT triggers its bioactivity, leading to vasodilation. Second, white blood cell filtering is an essential procedure in ABT, and it increases levels of IL-6 and complement 3 in the blood, which may contribute to reduced mean artery pressure.　Trend　Further investigations are warranted to address whether controlling the levels of vasoactive molecules would prevent AHABT.