A technique has been developed to examine the same G-banded human metaphase chromosomes, first in the light microscope and then in the scanning electron microscope (SEM). A structural involvement in chromosome banding was confirmed by a positional correlation between the G-positive bands observed in the light microscope and the circumferential grooves between the quaternary coils of the metaphase chromosomes, observed in the SEM. In further support of this the regions between the grooves showed a positional relationship with the G-negative or reverse (R) bands. The examination of slightly extended metaphase chromosomes in the light microscope demonstrated that the G-banding pattern corresponded to that described by the Paris nomenclature for metaphase chromosomes. The arrangement of the circumferential grooves of the same chromosomes, observed in the SEM, was shown to relate to that described by the Paris nomenclature for prometaphase chromosomes. Therefore, using the SEM it is possible to demonstrate the details of prometaphase banding in metaphase chromosomes.