Diarrhea become one of the main health problems in Indonesia that requires serious treatment. The villagers prefer to use herbal treatment to cure diarrhea, one of them is rambutan peel. The aim of this study was to reveal anti diarrheal effectiveness of rambutan peel’s (Nephelium lappaceum L.) ethanol extract. This research was an experimental test with the sample divided into 5 groups : negative control group (CMC), rambutan peel’s (Nephelium lappaceum L.) ethanol extract dose 350 mg, dose 700 mg,dose 1.400 mg, and positive control group. Analysis of the frequency of defecation used one way ANOVA test and followed by LSD, while the consistency of defecation used Kruskal Wallis test and followed by Mann Whitney test. The results test of frequency of defecation for group II, group III, and group IV showed significant difference with control group (p