Background: The objective of this study was to determine complete blood count (CBC) abnormalities in Libreville blood donors to advocate for hemoglobin pre-donation implementation and to take into account CBC results in blood donation qualification. Methods: This retrospective study was conducted with 4,573 blood donors in March 2016 and from January to April 2017. CBC was performed using SysmexXP-300 TM hematology analyzer (SYSMEX Corporation, Kobe, Japan). Results: Blood donors were predominantly males (83.7%) with an age ranging from 18 to 59 yrs. The abnormalities of leukocyte, platelet, and erythrocyte counts were determined in blood donors. Leukopenia and thrombocytopenia were significantly more common in men than women (29.02% vs 24.4%, p = 0.011 and 16.2% vs 7.5%, p < 0.001). Only 1.0% of women and 0.84% of men had leukocytosis, and 0.7% of women and 0.2% of men had thrombocytosis. Anemia was significantly more common in women compared to men (69.4% vs 45.0%, p < 0.001). Normocytic normochromic and normocytic hypochromic anemia were most common among Libreville blood donors with 39.4% and 23.6%; followed by microcytic normochromic (18.7%) and microcytic hypochromic (13.2%) anemia. Normocytic normochromic and normocytic hypochromic anemia were significantly more common in men than in women, whereas microcytic normochromic anemia was more prevalent among women compared to men (34.6% vs 13.9%, p < 0.001). Conclusions: The results of this study clearly show the need to perform a pre-donation hemoglobin test in blood donors and to take into account their hemogram in the blood donation selection process at the Libreville National Blood Transfusion Center.