Marine invertebrates are a rich source of sulfated polysaccharides with novel structures. Compounds dermatan sulfate–like has been reported in some marine species, however a few works describe the presence of these molecules in crustacean. Before that, we proposed to study the occurrence of dermatan sulfate (DS) in the shrimp specie L.schmitti, which is largely found on the Northeast coast of Brazil. The DS was isolated from shrimp tissues by proteolysis, complexation with ion-exchange resin, eluted with 3.0 M NaCl, fractionated with 1.0 acetone volume, purified by DEAE-Shephacell column eluted with 0.8M NaCl, submitted to enzymatic digestion by chondroitinases and structurally analyzed by ¹H and ¹³C nuclear magnetic resonance spectroscopy. The shrimp DS isolated showed a peculiar electrophoretic behavior, migrating between DS and HS in the PDA system. However it was susceptible only to degradation with chondroitin ABC lyases releasing mainly disulfated disaccharides. These data were confirmed by spectroscopy and disclosed the presence of the N-acetyl galactosamine residues 4-O and 6-O-sulfate. Furthermore were identified characteristic signals for both glucuronic and iduronic 2-O-sulfated residues. In order to evaluate its effects on leukocyte migration was used the peritonite inflammatory model in rats. Treated animals with shrimp DS in a concentration of 15 mg/kg showed a reduction in the cellular infiltration of 65%. In this same concentration, the protein total level in the peritoneal fluid reduced in about 50%. In all of the tested concentrations, the DS didn't change the qualitatively cellular composition in the peritoneal exudate. Although, further studies are necessary for the understanding of the polysaccharide role in the molecular mechanism during the imunologic response, the obtained data can suggest that the shrimp DS reduces the inflammatory response.