Details are presented of analyses of hemoglobins in blood samples from four newborn babies with hydrops fetal is using reversed phase and anion exchange high performance liquid chromatographic methodology. Three were homozygous for the a-thalas-semia-1 (SEA) deletion, and one was a compound heterozygote for the same deletion and the largerα-thalassemia-1 (Fil) deletion. All four babies hadβ,Gγ,Aγ, and 5 chains; these chains were present in Hb Bart's orγ4, Hb Portland-I (ζ2γ2), and Hb Portland-II (ζ2β). Hb H (β) could not be detected. The level ofζwas directly related to the level of B and, thus, the fetal age. A lower level of 5 chain was present in the baby with the compound heterozygosity because the large deletion (Fil) on one chromosome included theζandψζgenes. Circulating red cells, i.e. reticulocytes and nucleated red cells, were unable to synthesizeζchains, indicating that this capability must have ceased a few months prior to birth. Quantitative data obtained by chromatographic procedures were greatly influenced by the condition of the blood sample and the way it was stored, Hb Portland-II (ζ2β2) and Hb Bart's (γ4)are rather unstable when a red cell lysate is stored at 4°C; this is in contrast to Hb Portland-I (ζ2γ2) which appears to be stable. Samples can best be stored as washed red cells or red cell lysates at−70°C.