The community associated to the kelp Macrocystis pyrifera from the Beagle Channel (54°00´S; 68°20´W) was studied. Sixty-eight taxa including Algae (5), Porifera (indet.), Bryozoa (7), Nemertea (2), Annelida (10), Mollusca (22), Crustacea (15) and Echinodermata (7) were recognized. A seasonal sampling during one year showed differences in taxa composition when comparing (a) two different environments; (b) the spring-summer period and the autumn-winter period; and (c) the parts of the alga (fronds and holdfast).