Sulfated polysaccharides extracted from algae have important pharmacological properties. Therefore, the aim of this study was to characterize the sulfated polysaccharide (PLS) from the algae Hypnea musciformis and evaluate its protective effect on colitis induced by trinitrobenzene sulfonic acid in rats. The sulfated polysaccharide has a high molecular mass (1.24 x 105 g.mol-1). The rats were given PLS orally (10, 30 and 60 mg/kg, p.o.). The rats were killed on the third day, the part of the distal colon (5 cm) was excised and the macroscopic scores and wet weight were evaluated. Samples of the intestine were then used for histological evaluation and quantification of glutathione, malonyldehyde acid, myeloperoxidase, nitrate/nitrite and cytokines. Our results show that PLS reduced colitis and all the biochemical parameters analyzed. Thus, we conclude that PLS extracted from the seaweed H. musciformis reduced colitis in the animal model and may have an important promising application in inflammatory bowel diseases.