Bay leaf (Syzygium polyanthum (Wight) Walp) is not only can be used as food seasoning and flavoring but also as medicine. Indonesian National Agency of Drug and Food Control established bay leaf as one of the nine major medicinal plants. The aim of this study was to conduct in vitro bioactivities analysis as antidiabetic, antioxidant and toxicity of bay leaf water extract. Bay leaf used in this study was collected from the gardens of research center for science and technology (Puspiptek) Serpong, Tangerang Selatan Indonesia, dried and extracted steeping in boiled water. Antidiabetic was measured using α-glucosidase inhibition method; antioxidant was measured using DPPH free radical flushing activity method; toxicity test was measured using Brine Shrimp Lethality Test (BSLT). The resulst showed that the decoction of bay leaves showed antidiabetic (41.4% inhibition of a-glucosidase) and antioxidant (49.4% scavenging of DPPH) activities at sample concentration of 50 μg/ml and very low toxic effect on brine shrimp larvae (LD50> 1000μg / mL). The results suggest that bay leaf water extract has potential to be used in development of functional drink to reduce diabetic risk.