: Henna leaves (Lawsomia inermis Linn.) is traditional medicine that used to treat diabetes mellitus in Indonesia. Previous studies reported that Henna leaves extract showed in vitro and in vivo hypoglycemic activities. In the present study, for the first time antihyperglycemic activity of Henna leaves extract in aloxan-induced diabetic zebrafish (Danio rerio) was investigated. Four different extracts using n-hexane, ethyl acetate, ethanol 96% and distilled water were prepared by maceration technique. Each of them (2.50 mg/mL) was given to the alloxan-induced diabetic zebrafish, daily (for 3 days treatment period). Blood glucose levels of zebrafish were measured on 1st, 2nd, and 3rd days after the treatment. The distilled water was administered as a negative control and metformin (0.23 mg/mL) was administered as the positive control. The blood glucose levels were analyzed by using two-way analysis of variance (ANOVA) continued by Tukey test at p<0.05. All extracts were resulted significant antihyperglycemic effects in time-dependent manner (p<0.05). Furthermore, the extracts of n-hexane, ethyl acetate and ethanol 96% were exhibited antihyperglycemic effects, similar with metformin (p>0.05). The L. inermis Linn. leaves extracts are potential to be developed as new antidiabetic substances. Isolation of the active constituents which responsible to the antidiabetic activity need to conduct in further study..