Background: Millions of people worldwide use alternative health care systems, and traditional medicines are a crucial part of such systems. In contrast to contemporary pharmaceuticals, which are single molecules that have undergone rigorous testing, structural optimisation, and toxicological clearance, traditionally used herbal remedies are multi-constituent medicines, the safety and efficacy of which are dependent on the experiences of the practitioners. More than 80% of contemporary medications are obtained directly from natural sources (plants, microorganisms, cells, etc.) or their molecules/compounds. Plants are becoming recognised as prospective sources for drug development. Diarrhoea and other gastrointestinal diseases are treated using a variety of conventionally used medicinal herbs. Aim & Objective: The focus of the current study is on testing P. guajava ethanolic leaf extract for its potent anti-diarrheal properties, which have been demonstrated in computer-aided simulation tests confirmed the plant's potential for antidiarrheal action. Method: A grid-based docking strategy was used to determine the binding using the Auto Dock software. Merck Molecular Force Field was used to build the 2D structures of compounds, convert them to 3D, and then energetically reduce them up to arms gradient of 0.01. (MMFF). Result: Based on previously proven effects of flavonoids and on diarrhea. Two flavonoids i.e. quercetin and quercetin-3-arbinoside which were found in the ethanolic leaf extract of P.guajava was selected as lead molecules for current investigation. So, in current study an attempt had been made to elucidate the proposed anti-diarrheal mechanism of the action of selected lead compound (flavonoids) against muscarinic- M3 receptor by in -silico molecular docking. The result of molecular docking showing binding energy -5.81 & -4.32 kcal/mol for quercetin and quercetin-3-arbinoside respectively.