The research aimed to study Averrhoa bilimbi L extract immersed in edible coating, i.e. chitosan to prevent microbial attack on tomatoes. The extract was obtained from leaves of Averrhoa bilimbi L using maseration method. The experiment was designed with Completely Randomized Design using three treatments as follows: (1) Chitosan as edible coating, (2) Extract of Averrhoa bilimbi L as antimicrobial smeared onto tomatoes, and (3) Chitosan mixed with extract of Averrhoa bilimbi L and used as edible coating. Analysis used to test the quality of tomatoes were: hardness, weight loss, colour, titrable acid,acorbic acid, sugar and microbial attack. Result showed that chitosan mixed with extract of Averrhoa bilimbi L and used as edible coating gave the best result in maintaining quality of tomatoes based on analysis on hardness, weight loss, colour, titrable acid; acorbic acid and sugar. Extract of Averrhoa bilimbi L was succeed in prolong the shelf life on tomatoes into 25 days and prevented microbial attack.