The biomass of the benthic marine macroalgae from the inner Potter Cove was studied along a depth profile across different substrates during Antarctic summer. Macroalgal associations were identified by means of cluster analysis. Twenty-two species have been found in the study site, approximately half of the species present in the area. This paucity may be ex-plained by the strong preponderance of the brown algae Desmarestia anceps and D. menziesii, which are able to exclude other species by competition for light. The mean bio-mass of all macroalgae was 1390 g DW/m2 ± 1787 g DW/m2. Nine macroalgal asso-ciations were identified with different preferences for depth, substrate and the degree of expo-sure. Overall, there was a tendency of macroalgae to grow on fine substrates with increasing depth. Species rich-ness decreased at 20m depth, probably due to limiting light conditions. The results are discussed with respect to previ-ous studies in East and West Antarctica.