Abstract: The purpose of the study was to investigate the crude n-hexane, ethyl acetate and methanol extracts of Aphanamixis polystachya leaves for their antimicrobial, antioxidant, cytotoxic and thrombolytic activities. The leaves extracts were screened for major phytochemical compounds using in vitro established procedures. Antimicrobial and cytotoxic studies of the leaves extracts were conducted using disc diffusion and brine shrimp lethality bioassay methods, respectively, while an in vitro thrombolytic model was used to assess the clot lysis effect of the extracts with streptokinase as positive control. Antioxidant activity was evaluated by free radical scavenging activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide assay as well as total phenolic and flavonoid content. The leaves extracts were found to be a rich source of phytochemicals and among the extracts methanol extract was the most active against tested micro-organisms-Shigella dysenteriae, Staphylococcus aureus and Candida albicans. Compared to potassium permanganate with a median lethal concentration (LC50) of 11.27 μg mL-1 in the brine shrimp lethality assay, the LC50 of n-hexane, ethyl acetate and methanol extracts were 20.09, 36.33 and 60.12 μg mL-1, respectively. All the extracts showed significant clot lysis activity with reference to control. Notable antioxidant activity of the methanol extract was observed unlike the other extracts. The results of the study demonstrated bioactivities of the leaves extracts of A. polystachya and therefore further studies on the isolation and identification of active principles are required.