Objective: To investigate the cytotoxic, antioxidant and antibacterial activities of ethanolic and aqueous crude extracts of Nerium oleander (N. oleander) leaves. Methods: Cytotoxic activities were evaluated by WST-1 bioassay on two human cancer cell lines, namely human colon adenocarcinoma cell line HT-29 and human breast cancer cell line MDA-MB-231. The antioxidant property of N. oleander extracts was assessed by DPPH scavenging and β-carotene bleaching tests. The agar disc diffusion method was used for the determination of antimicrobial activity against different strains. Results: Using cell viability indices, the WST-1 test revealed that both extracts reduced cell viability in both cell lines. Our results also showed that aqueous extract was more active than ethanolic extract, with IC