Whole blood and purified hemoglobins from a patient heterozygous for Hb British Columbia were studied with various types of electrophoresis. Isoelectric focusing of whole blood in cylindrical polyacrylamide gels showed 3 major hemoglobin species at equilibrium: Hb A, Hb British Columbia, and an unidentified Hb with an isoelectric point of 7.15. In addition, a transient asymmetric hybrid band was observed between Hb A and Hb British Columbia; it had disappeared at equilibrium. Hb A2 was never present. Isoelectric focusing of purified Hbs A2 and British Columbia in various proportions, and gel permeation chromatography of them in equal amounts, indicated that the pI 7.15 component was a very stable hybrid. This hybrid was recovered from thin-layer isoelectric focusing in agarose. Electrophoresis on agar at pH 6.0 showed 3 hemoglobins: A2, British Columbia, and one of intermediate migration. On cellulose acetate at pH 9.2, only the 2 parent Hb components, A2 and British Columbia were seen. Thus, the single Hb recovered from agarose is probably the asymmetric hybrid alpha 2 delta beta British Columbia.