We describe an infant with hemoglobin D Ibadan-beta zero thalassemia whose hemoglobinopathy was initially detected by neonatal screening. This previously undescribed condition was confirmed by family studies and by globin chain analysis by mass spectrometric techniques. The case illustrates the importance to neonatal screening programs of confirmatory testing and of linkage with reference laboratories capable of globin chain analysis. Hematologic studies at 36 months of age suggested that the presence of hemoglobin D Ibadan had no deleterious effect on this child with heterozygous beta zero thalassemia.