Hemoglobin (Hb) Bart’s hydrops fetalis is the most severe form of alpha-thalassemia and has high mortality. It is caused by deletion of all four α-globin genes leading to a severe deficiency in α-globin and to the production of γ-globin tetramers, resulting in ineffective tissue oxygen delivery. Current preconceptional or prenatal screening policies for this disorder are comprehensive, but not all pregnancies with Hb Bart’s disease can be detected early before hydrops become apparent. We report here two cases with Hb Bart’s disease that escaped being detected until second trimester after hydrops fetalis occurred. These cases remind the clinicians that the importance of this well-characterized condition (alpha-thalassemia) should be reasserted despite a nationwide screening program is available. We also review the current status of prenatal screening and diagnosis of alpha-thalassemia.