Tetrodotoxin (TTX), is a potent neurotoxin found in genetically diversed organisms. Many TTX producing microorganism have also been isolated from TTX bearing animals. The TTX producing microbes found in four different phylum (Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes), the Proteobacteria are the dominating one. In most of the cases, TTX producing microbes are found in the intestine of the TTX producing vector indicating the origin of TTX through food chain. This paper reviews the TTX and its analogs and the geographic distribution of TTX in symbiotic microorganism and its production. Copyright © 2013 Elsevier B.V. All rights reserved.