A distributional study of the Cactaceae of Ohio utilizing both literature and herbarium records revealed the presence of two species. Opuntia compressa (Salisb.) Macbr. is native but infrequent in the state’s flora. It occurs primarily in sandy soil in two widely separated regions of the state: the southwest shore of Lake Erie and vicinity and the unglaciated Appalachian upland of southeastern Ohio. This disjunct pattern is likely related to a northern migration during a xerothermic period ensuing after the retreat of the Wisconsin glaciers. Opuntia macrorhiza Engelm. is introduced and naturalized only in the southwest corner of the state (Hamilton County), this naturalization being due to the creation of artificial xerophytic habitats, viz., the construction of railroad right-of-ways in gravel deposits. Both are variable species. However, the recognition of segregate species or even infraspecific taxa in Ohio appears unwarranted.