OBJECTIVE: Prostate cancer(PCa) is a major health concern. Calliandra portoricensis(CP) is traditionally known for its analgesic, anti-ulcerogenic and anticonvulsant properties. However, its antiproliferative properties for PCa still need to be investigated. METHODS: Antioxidant activities of CP were determined by 1,1-diphenyl-2-picryhydrazyl(DPPH) and hydroxyl(OH-) radicals-scavenging methods. PC-3 and LNCa P(androgen-refractory and androgendependent PCa-derived cell lines) were cultured and treated with CP(10, 50 and 100 μg/m L). Effects of CP on cells were determined by cytotoxicity assay(lactate dehydrogenase, LDH) and viability assay(sodium 3′-[1-(phenylaminocarbonyl)-3,4-tetrazolium]-bis(4-methoxy-6-nitro) benzene sulfonic acid hydrate, XTT). DNA fragmentation was detected by cell death detection enzyme-linked immunosorbent assay plus kit. CP was tested as an inhibitor of angiogenesis using chicken chorioallantoic membrane(CAM) assay. RESULTS: CP showed significant scavenging of DPPH and OH- radicals. CP significantly(P<0.05) inhibited lipid peroxidation in a dose-dependent manner. Precisely, CP(10, 50 and 100 μg/m L) inhibited PC-3 and LNCa P growth by 7%, 74% and 92%, and 27%, 73%, and 85% respectively at 48 h. CP had low toxicity in vitro at its half inhibitory concentration dose. Detection of cell death induced by CP at 50 μg/m L showed higher enrichment factors in LNCa P(7.38±0.95) than PC-3(3.48±0.55). Also, treatment with CP(50 μg/m L) significantly reduced network of vessels in CAM, suggesting its antiangiogenic potential. CONCLUSION: Calliandra portoricensis elicited antioxidant, antiangiogenic and antiproliferative effects in PCa cells. OBJECTIVE: Prostate cancer (PCa) is a major health concern. Calliandra portoricensis (CP) is traditionally known for its analgesic, anti-ulcerogenic and anticonvulsant properties. However, its antiproliferative properties for PCa still need to be investigated. METHODS: Antioxidant activities of PC-3 and LNCa P (androgen-refractory and androgen dependent PCa-derived cell lines) were cultured and treated with (DPPH) and hydroxyl (OH-) radicals-scavenging methods Effects of CP on cells were determined by cytotoxicity assay (lactate dehydrogenase, LDH) and viability assay (sodium 3 ’- [1- (phenylaminocarbonyl) -3,4-tetrazolium] 4-methoxy-6-nitro benzene sulfonic acid hydrate, XTT). DNA fragmentation was detected by cell death detection enzyme-linked immunosorbent assay plus kit. CP was tested as an inhibitor of angiogenesis using chicken chorioallantoic membrane (CAM) assay. RESULTS: CP showed significant scavenging (P <0.05) inhibited lipid peroxidation in a dose-dependent manner. Precisely, CP (10, 50 and 100 μg / mL) inhibited PC-3 and LNCa P growth by 7% 74% and 92%, and 27%, 73%, and 85% respectively at 48 h. CP had low toxicity in vitro at its half inhibitory concentration dose. Detection of cell death induced by CP at 50 μg / m L showed higher enrichment Factors in LNCa P (7.38 ± 0.95) than PC-3 (3.48 ± 0.55). Also, treatment with CP (50 μg / m L) significantly reduced network of vessels in CAM, suggesting its antiangiogenic potential. CONCLUSION: Calliandra portoricensis elicited antioxidant , antiangiogenic and antiproliferative effects in PCa cells.