Objective: Determination of the antidiarrheal activity of extract ethanol melinjo leaves (Gnetum gnemon L. (Linn.)) in Wistar male white rats induced by Escherichia coli and extract standardization has been performed. Methods: This research was conducted by in vivo method using white male rats of Wistar strain induced by Escherichia coli. The treatment group was divided into 6 groups: normal, negative control, positive control, and groups with doses 150, 300, and 600 mg/kg BW. Negative control was given Na-CMC and positive control Gentamicin. The initial time diarrhea occurred 24-30 h after administration of Escherichia coli suspension. Results: The results of the phytochemical screening of the ethanolic extract of melinjo contain secondary metabolites of flavonoids, steroids, tannins, and saponins. Standardization of the extract ethanol melinjo leaves (Gnetum gnemon L.) meet the predetermined standards, while the acid insoluble ash content parameters did not meet the predetermined standards. The parameters feces weight, feces consistency, frequency diarrhea, body weight, number of Escherichia coli colonies feces dose 600 mg/kg BW had an effect that was almost close to positive control. The results showed that anti-diarrheal effect dose 150 mg/kg BW 35.75%, dose 300 mg/kg BW 43.02%, dose 600 mg/kg BW 50.14%. This shows that ethanol extract melinjo leaves dose 600 mg/kg BW wasn’t significantly different from the positive control (p<0.05). Effective Dose (ED50) Ethanol Extract Melinjo Leave as antidiarrheal was 578.2468 mg/kg BW. Conclusion: Extract ethanol melinjo leaves (Gnetum gnemon L. (Linn)) dose 600 mg/kg BW has the potential to be used as antidiarrheal and its extract meet the predetermined standards, except the acid insoluble ash content parameters did not meet the predetermined standards.