The features offoliar epidermis and stomata are studied in nine genera representing all the four tribes of the subfamily Oldfieldioideae of the family Euphorbiaceae. On both sides of the leaf, the cuticle is generally smooth with more or less straight epidermal anticlinal walls. The epidermal cells are polygonal and their size varied with species on both sides. The costal cells are either distinct (Dissiliaria, Oldfieldia, etc.) or indistinct (Caletieae). In the taxa examined, the stomata are confined to the abaxial epidermis and diffusely orientated except in Caletieae. They are basically of brachyparacytic type; however, they are anomocytic in Androstachys and of a special type in Mischodon. A systematic consideraton of these features showed that they aer not only useful in revealing relationships within the subfamily but also of acid in the classification.