Women contribute modestly to the blood supply in the Eastern Mediterranean region. The capability, opportunity, motivation-behavior model can be used to understand this phenomenon further. The framework suggests that capability, opportunity, and motivation are prerequisites for behavior. Most of the previously published research in Saudi Arabia has focused on motivation. This study aimed to evaluate the capability of donating blood among women who present to blood banks for donation and to compare the findings with those of men. A retrospective analysis of blood donor records was conducted to identify the outcomes of donor evaluation for women and men in a hospital blood bank over 13 months. Of 10,175 visits for whole blood donation, 9138 were by men and 1037 were by women. Donation was successful in 8641 visits by men (94%) and 616 visits by women (59%). In men, the most common cause of deferral was responses to the donor history questionnaire; in women, it was low hemoglobin. Compared with men, women were 12 times more likely to be deferred when presenting to donate blood. Logistic regression analysis revealed that women were less likely to be deferred for low hemoglobin levels as their age increased. The capability of women to donate blood is significantly lower than that of men, even if they are motivated and have opportunities. Anemia is the most common cause of deferral in women. Interventions are necessary to prevent, screen, and manage anemia in women in general and potential blood donors in particular.