Diarrhoeal disease is a leading cause of mortality and morbidity in developing countries. World Health Organization in Diarrhoeal Disease Control Programme has given a special emphasis on the use of traditional medicines in the control and management of diarrhoea. Mebarid syrup, Enterocin syrup and Kutajarishta syrup are Ayurvedic formulations, consist of medicinal herbs which are indicated in diarrhoea and dysentery. Antidiarrhoeal effect of Mebarid, Enterocin, Kutajarishta alone and in combination with aqueous Black pepper extract were subjected to pharmacological evaluation. Antidiarrhoeal effect was evaluated in castor oil and magnesium sulphate induced diarrhoea while antimotility and antisecretory effect was evaluated in charcoal meal test and castor oil induced intestinal secretions in mice. Thus book provides the information about mechanisms of antidiarrhoeal activity of Ayurvedic formulation. Aqueous Black pepper extract produced a significant increase in the antidiarrhoeal, antimotility, and antisecretory effect of Mebarid, Enterocin, Kutajarishta explaining the significance of Black pepper in Ayurvedic antidiarrhoeal formulation.