Aegle marmelos despite its traditional usage as an antidiarrhoeal activity there is limited information regarding its mode of action in infectious forms of diarrhea. Hence we have studied the hot water soluble pectic polysaccharide (HWSPP) isolated from aqueous extract of semi-ripe fruit pulp of A. marmelos for its antimicrobial activity and antidiarrhoeal activity. We have studied in vitro using pathogenic bacterial strains like Escherichia coli O114, Vibrio cholerae Inaba 569B, Entamoeba histolytica HM1: IMSS. At a concentration of 500 µg/ml HWSPP showed nearly 32% anti-vibriocidal activity wrt control after 48h. Ciprofloxacin under similar experimental condition showed 33% anti-vibriocidal activity at a dose of 500 µg/ml wrt control after 48h. After 48h HWSPP (500 µg/ml) showed 18.7% anti-E. coli activity wrt control, whereas, under the same experimental condition the antibiotic ciprofloxacin (500 µg/ml) showed 32% inhibition. HWSPP (200 µg/ml) showed moderate anti-amoeba activity (40%) against Entamoeba histolytica (HM1: IMSS). Under similar experimental condition the reference compound Caryophyllene α-oxide (200 μg/ml) showed 47% anti-Entamoeba histolytica activity. The in vivo antidiarrhoeal activity of the HWSPP in mice showed dose dependent activity where, significant reduction of defaecation has been observed at a dose of 5 mg/kg body weight with respect to the control.