Separation of normal human serum, to which hemoglobin had been added, by conventional starch zone electrophoresis resulted in three characteristic patterns which also permitted the ready identification of the serum haptoglobin group. The haptoglobin hemoglobin complex from Group 1-1 had the fastest mobility and that of Group 2-2 the slowest. The heterozygote Group 2-1 had an intermediate mobility. Immunologic differences between the haptoglobin hemoglobin complexes of the three groups could not be detected.

Some of the variations in the reported electrophoretic and ultracentrifugal patterns of normal human serum could be reasonably ascribed to the group variation of the haptoglobins in man. The physical studies imply that the proteins characteristic of the heterozygote differ in size and charge from those present in either of the two homozygotes and indicate that the genetic control of the synthesis of the serum haptoglobins is probably exceedingly complex.