In Malaysia, Piper sarmentosum or 'kaduk' is commonly used in traditional medicines. However, its biological effects including in vivo embryonic toxicity and tissue regenerative properties are relatively unknown. The purpose of this study was to determine zebrafish (Danio rerio) embryo toxicities and caudal fin tissue regeneration in the presence of P. sarmentosum aqueous extracts. The phytochemical components and antioxidant activity of the extract were studied using GC-MS analysis and DPPH assay, respectively. Embryo toxicity tests involving survival, heartbeat, and morphological analyses were conducted to determine P. sarmentosum extract toxicity (0-60 µg/mL); concentrations of 0-400 µg/mL of the extract were used to study tissue regeneration in the zebrafish caudal fin. The extract contained several phytochemicals with antioxidant activity and exhibited DPPH scavenging activity (IC 50 = 50.56 mg/mL). Embryo toxicity assays showed that a concentration of 60 μg/mL showed the highest rates of lethality regardless of exposure time. Slower embryogenesis was observed at 40 µg/mL, with non-viable embryos first detected at 50 µg/mL. Extracts showed significant differences (p < 0.01) for tissue regeneration at all concentrations when compared to non-treated samples. In conclusion, Piper sarmentosum extracts accelerated tissue regeneration, and extract concentrations at 60 µg/mL showed the highest toxicity levels for embryo viability. Natural products have been frequently used as dietary supplements for health promotion and for culinary uses due to their herbaceous scents and flavours. Piper sarmentosum is one particular natural product with several medicinal effects including anti-cancer and fracture healing properties 1, 2. P. sarmentosum is a medicinal plant found in tropical countries, such as Indonesia, the Philippines, and Malaysia. The plant is widely consumed in the Asean region for its medicinal benefits. Aqueous extracts from P. sarmentosum have been found to produce anti-cancer effects on human liver cancer and Chang's cell lines 2, 3. However, further study on Chang's cell lines which originally derived from normal liver has found this cell is indistinguishable from HeLa (human cervical cancer) by STR PCR 4. P. sarmentosum extracts have been reported to produce aid in healing fractures; such extracts contain flavonoid compounds that reduce bone loss and increase bone strength in ovariectomised rats 1 .