Epigallocatechin 3-gallate (EGCG), one of the major catechins of tea, was isolated from thedecaffeinated, crude methanolic extract of Indian green tea (Camellia sinensis L. O. Kuntze)using chromatographic techniques. EGCG was then screened for antidiarrhoeal activity against30 strains (clinical isolates) of V. cholerae, which is a well known Gram negative bacillusfunctioning as the pathogen of cholera. V. cholerae strains like V. cholerae 69, 71, 83, 214, 978,1021, 1315, 1347, 1348, 569B and ATCC 14033 were inhibited by EGCG at a concentration of 25µg/ml whereas V. cholerae 10, 522, 976 were even more sensitive, being inhibited at 10 µg/mllevel. However, V. cholerae DN 16, DN 26, 30, 42, 56, 58, 113, 117, 564, 593, 972 and ATCC 14035were inhibited at 50 µg/ml level of EGCG. Only four strains were inhibited at 100 µg/ml. Inthis study the isolated compound was found to be bacteriostatic in its mechanism of action. Inthe in vivo experiment using the rabbit ileal loop model two different dosages of EGCG (500 µg/ml and 1,000 µg/ml) were able to protect the animals when they were challenged with V.cholerae 569B in the ileum.