As part of a research project on the natural products of marine algae, we have studied the content of agar agar in Acanthophora spicifera (Vahl) Borgesen. The study was conducted in La Guaira and Isla Grande near Colón, Panamá. The average amount of agar was 43.3% and the content of 3,6- anhidrogalactosa was 0.2940 g. There was no seasonal variation in the content of agar, neither in any other reological properties of agar extracted.