A phylogenetic analysis of 566 plastid rbcL gene sequences representing nearly all eudicot families (a total of 314 families; eight photosynthetic and four parasitic families are missing) was performed, and bootstrap re-sampling was used to assess support for clades. Based on these data, the ordinal classification of eudicots is revised following the previous re-classification of angiosperms by the Angiosperm Phylogeny Group (APG). Putative additional orders are discussed (e.g. Dilleniales, Escalloniales, Vitales) and several additional families are assigned to orders for further updates of the APG classification. The use of rbcL alone in such a large matrix was found to be practical in discovering and providing bootstrap support for most orders. Combination of these data with other matrices for the rest of the angiosperms should provide the framework for a complete phylogeny to be used in macro-evolutionary studies.