The nutritional compositions of 40 antarctic macroalgal species from the western Antarctic Peninsula were analyzed during two periods, one early in the growing season and one late in the growing season. Protein levels were greater than those reported in macroalgae from temperate and tropical latitudes. These high protein levels are presumed to be related to the nutrient-rich waters in which the macroalgae reside. There was a significant interaction between time of season and species as well as taxonomic grouping for the species collected both seasons. A total of 36 species were further analyzed for total percent N and C and their C:N ratios. Total nitrogen [% dry weight (dw)] levels were found to be above critical nitrogen levels ( 1.5%dw) reportedly needed for maximum growth in all but two of the species examined. The C:N ratios were found to be low with respect to those published from other latitudes and similar to those reported in the waters off the western Antarctic Peninsula. Nineteen species had C:N ratios below 10:1, which is half of the 20:1 C:N ratio reported as a mean for benthic marine plants from temperate and tropical latitudes. Analysis of nutritional composition and elemental content yielded no correlations between protein levels and nitrogen contents when all macroalgae were combined. Our results support the general hypothesis that nitrogen is not a limiting factor for protein production of antarctic macroalgae.