<b>Assessment of Bioactive Activity of Blackberry Seed Extract</b> The aim of this study was to determine the bioactive activity of the blackberry Rubus laciniatus seed extracts. Total phenolic and total antioxidant activity of blackberry seed extracts were assessed with respect to two extracting solvents absolute ethanol and absolute acetone and two extracting techniques hot extraction at 40°C and cold extraction at 26°C . Proximate analysis showed that blackberry seeds contained 12.12 moisture, 8.00 protein, 0.74 fat, 2.15 ash and 76.99 total carbohydrate. The antioxidant activities of blackberry seeds were determined by evaluating total phenolic activity by gallic acid equivalent GAE , total antioxidant capacity by ascorbic acid equivalent AAE content and ferric reducing powder assay. The tested sample showed variable amount of total phenolic content 33.21 56.56 mg GAE g of dry extract , total antioxidant capacity 75.46 82.42 AAE g and reducing power 0.23 0.26 depending on different extraction techniques and solvents used. Higher amount of extract, total antioxidant capacity and reducing power were obtained for hot extraction technique. As compared to cold extraction technique, higher extract yields 7.48 vs 7.19 for ethanol and 4.35 vs 4.28 for acetone and other properties were obtained by hot extraction for a given solvent. Ethanol extract with hot extraction technique gave total phenolic content as 56.56 mg GAE g of dry extract, total antioxidant capacity as 82.42 AAE g and reducing power as 0.26 at extract concentration of 250 µg ml. The overall observations of the present experiment indicated that hot ethanol extract of blackberry seeds have strong antioxidant property and bioactive activity. Blackberry seed, Total phenolic content, Antioxidant activity, Hot and cold extraction 1597-1605 Issue-5 Volume-2 Most. Sajeda Begam | Pabitra Chandra Das | Md. Nur Hossain | Abdullah Iqbal