Betel leaf (Piper betle L.) contains flavonoids, tannins, essential oils and alkaloids. Flavonoids inhibit the release of acetylcholine and intestinal contractions while tannins reduce intestinal peristalsis. Essential oils and alkaloids prevents microorganisms from growing and eradicate them in the intestine. This research examined the antidiarrheal activity of betel leaf ethanol extract in white rats (Rattus norvegicus). Antidiarrheal activity test of betel leaf ethanol extract was carried out by administering 1 ml of oleum ricini to rats orally as an induction of diarrhea. An hour later, the rats were treated with ethanol extract of betel leaves at different doses of 200, 300 and 400 mg/kgbw, loperamid HCL as positive control and 0.5% Na-CMC as negative control orally. Several parameters were observed for 5 hours during the diarrhea including, onset of diarrhea, faecal consistency, diarrhea frequency, and duration of diarrhea. The results of ANOVA statistical test showed a significant value of each test parameter is p <0.05, indicating that H0 was rejected while H1 was accepted. The results also confirmed the significant differences between treatment group and control group. The results were also supported by the outcome of Tukey HSD average difference test which also indicated that the ethanol extract of betel leaf at doses of 200, 300, and 400 mg/kgbw provided antidiarrheal activity in white rats, with the best effect at a dose of 400 mg/kgbw.