The foraminiferal superfamily Soritacea belongs to the suborder Miliolina and is divided in two families, Peneroplidae and Soritidae, the latter one comprising two subfamilies, Archaiasinae and Soritinae. Phylogenetic relationships of 11 genera of soritid foraminifera were investigated by sequencing the complete SSU rDNA gene for 25 specimens. Additionally, partial SSU rDNA sequences were obtained from another 15 specimens of Soritinae. DNA sequence analysis confirms the monophyly of each family. Caribbean Archaiasinae form a monophyletic clade with Pacific Laevipeneroplis at the base. The genus Parasorites apppears as a sister taxa to Soritinae. Complex morphological features that characterize the genus Marginopora seem to have evolved independently at least twice, as the examined representatives cluster within two other soritine genera. Molecular analysis further shows that Sorites orbiculus and Sorites marginalis represent two different morphotypes of one species. Our data indicate that morphological changes and acquisition of new endosymbiont types in each group played an important role in the adaptation and radiation of Soritacea.