Traditional sources of taxonomic characters in the large and taxonomically complex subfamily Apioideae (Apiaceae) have been confounding and no classification system of the subfamily has been widely accepted. A restriction site analysis of the chloroplast genome from 78 representatives of Apioideae and related groups provided a data matrix of 990 variable characters (750 of which were potentially parsimony-informative). A comparison of these data to that of three recent DNA sequencing studies of Apioideae (based on ITS, rpoCl intron, and matK sequences) shows that the restriction site analysis provides 2.6-3.6 times more variable characters for a comparable group of taxa. Moreover, levels of divergence appear to be well suited to studies at the subfamilial and tribal levels of Apiaceae. Cladistic and phenetic analyses of the restriction site data yielded trees that are visually congruent to those derived from the other recent molecular studies. On the basis of these comparisons, six lineages and one paraphyletic grade are provisionally recognized as informal groups. These groups can serve as the starting point for future, more intensive studies of the subfamily.