The aim of the study was to find out the phytochemical evaluation, antioxidant, cytotoxic and thrombolytic activity from the leaves of the methanolic extract of the plant of Polyalthia suberosa Roxb. Phytochemical analysis of Polyalthia suberosa Roxb displayed the presence of alkaloids, saponins and tannin types of compounds. The anti-oxidative effect was evaluated using DPPH free radical scavenging activity method. The methanolic extract of Polyalthia suberosa Roxb. leaves is found to have antioxidant activity that will be the IC50 value of standard ascorbic acid for DPPH was 1.85 µg/ml and methanol extract of Polyalthia suberosa Roxb was 8.48 µg /ml. The methanol crude extract of Polyalthia suberosa shows moderate cytotoxic activity against the brine shrimp nauplii. The LC50 value of methanol extract was 0.3119 mg/mL compared with the LC50 value of standard (0.0171 mg/mL). Addition of 100 μl SK, a positive control (30,000 IU), to the clots and subsequent incubation for 90 minutes at 37 °C, showed 88.49% lysis of clot. On the other hand, distilled water was treated as negative control which exhibited a negligible percentage of lysis of clot 10.44%. The results indicated that the extract has moderate antioxidant, cytotoxic and thrombolytic activities.