A ceramiaceous red alga, Ceramium stichidiosum J. Agardh was found for the first time in waters of Magellanic Strait, Chile. Thalli are usually epiphytic on other macroalgae such as Mazzaella laminarioides (Bory) Fredericq and Sarcothalia crispata (Bory) Leister. They have fully corticated axes with alternate to dichotomous branches, straight tips and six periaxial cells per each axial cell. This report extends the distribution limit of C. stichidiosum from the X Región de los Lagos (42º 58'S; 74º 19'W) to the XII Región de Magallanes (53°37'S; 70°59'W).