Diarrheal illness is the second-most common cause of death in under-five children. Worldwide, it results in about 1.7 billion illnesses and 525,000 deaths among under-five children annually. It is the leading cause of malnutrition among under-five children. Different people use medicinal plants to treat diarrhea. The present study aimed to review the medicinal plants used to treat diarrhea by the people in the Amhara region and to diagnose whether the antidiarrheal activities of the medicinal plants have been confirmed by studies using animal models. The author searched 21 articles from worldwide databases up to December 2022 using Boolean operators ("AND" and "OR") and the terms "ethnobotanical studies," "ethnobiology," "traditional medicine," "ethnobotanical knowledge," and "Amhara region." From the 21 studies reviewed, 50 plant species grouped into 28 families were reported to treat diarrhea by the people in the Amhara region. The top most used families were Lamiaceae (12%), Fabaceae (8%), Asteraceae, Cucurbitaceae, Euphorbiaceae, and Poaceae (6% each). The modes of administration of the plant parts were orally 98.88% and topically 1.12%. The different extracts of 18 (or 36%) of the medicinal plants traditionally used to treat diarrhea by the people in the Amhara region have been proven experimentally in animal models. The people in the Amhara region use different medicinal plants to treat diarrhea. Most of them take the medicinal plants orally. The traditional claim that 60% of medicinal plants are antidiarrheal has been confirmed in in vitro studies.