Low molecular weight fucoidan F-LMW-H10 has been examined activity against dyslipidemia. The research was published in journal of Y Hoc Quan Su number 273 in July 2011. To have a solid database for further research steps followed to develop pharmaceuticals of brown algae in Nha Trang bay, the authors conducted acute oral toxicity and subchronic oral toxicity of this products on guinea pig. The results showed that no significant toxicological changes were observed when 2580mg/kg body weight per day, during 7 days fucoidan administration to guinea pig and 1400mg/kg guinea pig body weight/day, given continuously for 3 months. Fucoidan caused no significant changes on the development of the animals body weight, REC, hemoglobin, limphocyte, monocyte, neutrophils, basophilus, the number of white blood cells, platelets, the activity of the enzyme AST (SGOT), ALT (SGPT) , urea, creatinine in the blood of laboratory rats and do not affect internal organs (liver, kidney, spleen) of experimental animals.