The plant Morinda pubescens (Rubiaceae) is a small, ever green plant which is native to southern India and it has been reported to possess a number of medicinal properties. The purpose of present study was to evaluate the antidiarrhoeal activity of the ethanolic extract of the roots of Morinda pubescens which is used traditionally as folk medicine, by using castor oil induced diarrhoea model. The parameters of this study were number of diarrhoeal episodes and mean weight of stool of mice. The percentage protection in extract treated animals showing diarrhoea was compared with castor oil treated and loperamide treated animals. The results revealed that the ethanolic extracts significantly reduced diarrhoea in mice with reduction in weight of stools.