Anticoagulant and antithrombotic properties of sulfated-polysaccharides (SP) from marine algae are extensively exploited. However, reports on the vascular effects of SP from red algae are rare in the literature. The polysaccharide from Solieria filiformis (Sf-SP) was isolated by ion exchange chromatography, analyzed by agarose gel electrophoresis and tested in male Wistar rats. The inflammation studies were performed using the paw-edema model and the relaxant activity in isolated aorta pre-contracted with phenylephrine. The anticoagulant effect was evaluated by the test of partial thromboplastin activation time. The SP (1 mg/kg) was not anti-inflammatory, but induced acute edema with maximal activity at 30 min (0.35 +/- 0.04 mL) compared to controls (0.05 +/- 0.03 mL). Cumulative addition of Sf-SP in phenylephrine-contracted tissues produced relaxation with maximal inhibition of 69% (IC50 29.3 +/- 9.0 microg/mL) at 300 microg/mL in comparison to controls (0.51 +/- 0.09 g). Sf-SP also extended human plasma coagulation time by 2.1 times. These substances could be used as important tools for the study of vascular alterations.