The distribution of encrusting Pneophyllum-Fosliella plants (Corallinaceae, Rhodophyta) on leaves of the seagrass Amphibolis antarctica was examined in terms of density, cover and relative fertility of the epiphytes on host plants from a sublittoral and a eulittoral environment. Significantly greater epiphyte cover, density and (in most cases) relative fertility occurred on sublittoral hosts. In both environments epiphyte cover, density and (usually) relative fertility were significantly greater on outer leaves in an Amphibolis cluster than on inner leaves. Cover, density and relative fertility also were significantly greater on distal segments of Amphibolis leaves as compared to proximal segments. No significant differences in any parameter, however, occurred between adaxial and abaxial surfaces of particular sets of leaves. The data are discussed in relation to the potentially adverse effects of epiphytes on the host plants.