BackgroundFor transfusion purposes, blood donors must be accepted both in clinical and serological evaluations and must not have excluded their own donation using the confidential unit exclusion.AimThe objective of this study was to verify whether blood donors who choose self exclusion are more likely to be positive in serological tests than donors who do not.MethodsA cross-sectional analysis was carried out of 51,861 consecutive whole blood donations from January 2004 to December 2008 at a public blood bank in Londrina, Southern Brazil.ResultsSelf exclusion was chosen in 1672 (3.2%) donations, most frequently by first-time blood donors (p-value < 0.0001), by blood donors from external collections (p-value < 0.0001), by men (p value < 0.0001) and by under 30-year-old donors (p-value < 0.0001). The frequency of positive serology was 5.3% in the group that chose self exclusion and 3.5% in the group that did not choose self exclusion (p-value < 0.0001).ConclusionsThese results show that confidential unit exclusion used in this blood bank is effective and is inexpensive. However, the diagnostic power to detect blood-borne infections was low and resulted in the discard of a high number of blood bags without any direct or indirect serologic markers of pathogens. The use of confidential unit exclusion could be replaced with molecular tests to screen blood donors.