The Cd technique was applied to two cases of dicentric attached X chromosomes (XpXp and XqXq) and to cells from an established cell line of tumor origin (MaNo9) in which dicentrics with two active centromeres were present and dicentrics with one active and one inactive centromere. It was confirmed that the Cd technique discriminates between active and latent centromeres, and it was demonstrated that true dicentrics and dicentrics with one latent centromere can co-exist in the same cells. This indicates that the mechanism of centromere inactivation is a phenomenon that is specific to each chromosome and not generalized at the level of the individual cell.