Small peridinioid dinoflagellate cysts are abundant in Paleocene strata underlying the Savannah River Site and surrounding area of South Carolina, U.S.A. They are thin-walled and light colored, have one apical and two antapical horns, and show a high degree of intraspecific variability. They occur in low diversity assemblages. The samples in this study are from three lithostratigraphic units, the lower Ellenton, upper Ellenton, and Snapp formations. Some of the species are useful stratigraphic markers in the Paleocene strata of this area. Paleoenvironments include upper delta plain, lower delta plain, and shallow clastic shelf; some may represent fresh or brackish water environments. All species studied belong to the family Peridiniaceae and are assigned to eight genera. These are Alterbidinium, Arvalidinium, Deflandrea, ?Isabelidinium, Phthanoperidinium, Senegalinium, Spinidinium, and Vozzhennikovia. The seven new species described here are Alterbidinium ellentonense, Arvalidinium cristatum, Deflandrea lucyedwardsiae, Phthanoperidinium paleocenicum, Senegalinium pallidum, Senegalinium simplex, and Spinidinium bellum.