Abstract. Armoured scale insects are economically important parasites of woody plants and grasses. They are promising subjects for the evolutionary study of physiology (no complete gut), genetics (chimerism, paternal genome elimination, frequent parthenogenesis) and coevolution (with host plants, parasitoids, Septobasidium fungi, endosymbiotic bacteria). Little phylogenetic work has been accomplished with armoured scales, and uncertainty surrounds their classification. Here, we report the phylogenetic results of Bayesian and parsimony analyses of 705 base pairs of Elongation Factor 1α and 660 base pairs of 28S from eighty-nine species of armoured scale insects, representing forty-seven genera and five tribes in the subfamilies Diaspidinae and Aspidiotinae, together with two outgroups. 28S was aligned based on a secondary structural model. Our results broadly corroborate the major features of the existing classification, although we do not find perfect monophyly of any of the traditionally recognized subfamilies or tribes. The subfamily Aspidiotinae is paraphyletic with respect to the subfamily Diaspidinae. Diaspidinae consists of two main clades that only roughly correspond to the tribes Lepidosaphidini and Diaspidini. Diaspidini is nearly monophyletic, except that it includes a single aspidiotine species. Other members of the tribe Aspidiotini form a clade, except that the clade includes a single species of Leucaspidini and excludes Maskellia and Pseudaonidia. Our results weakly support the hypothesis that the most recent common ancestor of the Diaspididae had adult females that were permanently enclosed within the derm of the second instar (the pupillarial habit) and had diploid adult males that eliminated their paternal genomes during spermatogenesis (late paternal genome elimination).