The study was designed to investigate the effect of brown algae (Sargassum subrepandum) ethanolic extract on obesity and is complications induced by high fat diet in rats.Thirty six rats were divided into two main groups, the first group (Group 1, 6 rats) still fed on basal diet and the other main group (30 rats) was with high fat diet (HFD) for 8 weeks which classified as follow: group (2), fed on HFD as a positive control; group (3), fed on HFD containing 0.25 % BAE; group (4), fed on HFD containing 0.50 % BAE; group (5), fed on HFD containing 0.75 % BAE and group (6), fed on HFD containing 1.0 % BAE. At the end of the experiment, rats of normal group increase in its amount by 90.11% when compared to the base line. Rats of the obese group increased by the rate of 147.02% when compared to the base line. Also, addition of 0.25, 0.50, 0.75 to 1.00% of BAE induced significant (p≤0.05) decreasing on body weight of the obese rats when compared to the starting point of the experiment. Also, BAE was effective in protecting against obese complications including lower the serum glucose level, inhibithepatotoxicity through liver serum enzymes-lowering activity, improvement of the serum immunological parameters and decreasing rate on the formation of MDA in serum, in evidence of lipid peroxidation and oxidative stress. In conclusion, we recommended like of that algae extracts by a concentrations ranged 0.25-1.0 % amount to be included in our daily diets