Smilax goyazana is a dioicous species occurring very commonly in the Brazilian cerrado vegetation. Leaves from male and female plants were compared in size and anatomical structure. No differences in size were found. Female plants presented higher stomatal density than the male ones. All other qualitative and quantitative parameters did not show differences related to sex. The leaf blade is amphistomatous. Only spongy mesophyll is present. In the midrib, there are three vascular bundles that fuse into one bundle in about the second third of the foliar length. Idioblasts containing calcium oxalate occur randomly in the petiole and leaf blade. No starch or tannins were evidenced. Nervation is acrodromous. S. goyazana presents structures similar to other Smilacaceae, however, in the whole, it presents distinctive characteristics from other species of the genus.