Sargassum is a source for many metabolites, including alginic acid, alginates, sulfated fucoidans, pigments, oils, sterols, and mannitols. The present study is the first attempt to examine Sargassum binderi (Sonder) J. Agardh, a tropical brown seaweed, using an expressed sequence tag (EST) approach. Single-pass 5′ sequencing of 2304 cDNA clones generated 1876 ESTs of good quality, from which 1270 tentative unique genes (TUGs) consisting of 991 singletons and 279 contigs were obtained. Approximately 39.5% of the TUGs from S. binderi showed significant matches to the existing data bases and were further divided into nine subcategories: metabolism (24.9%); transcription and translation (22.5%); cellular processes (7.2%); protein folding, sorting, and degradation (5.6%); signaling (2.8%); membrane and transport (3%); receptor (1.1%); other functions (4.2%); and unknown proteins (28.7%). The sequences were compared with ESTs from Laminaria digitata (Hudson) J. V. Lamour.