A study was undertaken to evaluate the in vitro and in vivo antidiarrhoeal pote . Of the 35 tested pathogenic diarrhoea causing strains, the extract was found to be mostly active against the strains of Vibrio cholerae, followed by Escherichia coli and Shigella spp. The in vitro activity was found to be comparable to that of ciprofloxacin. Further, Aegle marmelos root extract (AMRE) treated animals showed significant inhibitory activity against castor oil‐induced diarrhoea. The results so obtained thus established the efficacy of AMRE as an effective antidiarrhoeal agent.