Summary. Electrophoretically detectable haemoglobin abnormalities are readily identified in umbilical cord blood haemolysates by cellulose acetate electrophoresis, followed by citrate agar electrophoresis of those samples exhibiting an abnormality, and, if necessary, by globin electrophoresis. In samples from 9224 Black newborns, the prevalence of all such abnormalities was about 13%, with 12 cases of sickle‐cell anaemia, seven of Hb‐SC disease and five of Hb‐S β thalassaemia. Clinical and haematologic manifestations of these conditions usually appeared in the first few years of life. The prevalence of sickle‐cell trait was about 7%, Hb‐C trait 2%, and Hb Bart's 5%. Several new or rare haemoglobins, both adult and foetal, were found in individual families.Of 7006 White newborns, 76 or 1.1% had electrophoretically detectable haemoglobin abnormalities, all in the simple trait condition. Sixty‐one of these (0.8% of the total) had Hb‐Bart's and 10 had adult variants—four Hb S, four Hb C, one Hasharon and one unidentified α chain variant. Five samples contained structural γ chain abnormalities. One new variant—Hb‐F Dickinson (Aγ97 HisÅg), was found in two siblings.