Background: In this study, Fucoidan a type of polysaccharide extracted from Turbinaria conoides was subjected to invivo acute toxicity, sub-acute toxicity study, and invivo anticancer study to find fucoidan effect on Sprague Dawley rat (SD rats). An acute toxicity test was executed on matured Sprague Dawley rats. Result:They were administered with a single dose of 500mg/kg of fucoidan extract for 14 consecutive days and their general behavior, mental and physical changes along with mortality were observed and then the SD rats were subjected to the Sub-acute test and they were administrated with 50mg/kg, 100mg/kg, and 200mg/kg of fucoidan through oral gavage along with Tween 20 for 28 consecutive days and on the 29 day the animals were sacrificed and their vital organs were dissected and analyzed for noticeable signs of toxicity. Thus the study was extended to invivo anticancer analysis based on the results obtained from the acute and sub- acute toxicity studies to find the breast anticancer potential of the fucoidan. 250 mg/ml of test sample fucoidan was administered to 25mg/kg DMBA induced group animals (breast carcinoma induced animals) and it was compared with 20mg/kg of standard drug Fluorouracil treated animals. From the results, it was found that test animals in Acute and Subacute analysis test groups injected with fucoidan extracted from Turbinaria conoides showed no significant changes in the test groups compared to the control groups on further analysis. Conclusion SD rats injected with 25mg/kg of DMBA showed significant results on treating it with 250mg/kg of test compound fucoidan extracted from Turbinaria conoides compared with 20mg/kg of standard drug Fluorouracil thus it is concluded that our test compound contains the necessary pharmacological potential in it.