This article presents an overview of various types of marine toxins and their toxicological significance in the context of biotechnological research and development. The characteristics and toxic potentials of different marine toxins highlighted in this chapter are of Okadaic acid (OA), dinophysistoxin-1 (DTX1), dinophysistoxin-3 (DTX3), Pectenotoxin-1 (PTX1), Pectenotoxin-2 (PTX2), pectenotoxin-3 (PTX3), pectenotoxin-4 (PTX4), yessotoxin. 45-hydroxyyessotoxin (45-OH, YTX), Ciguatoxin, Prorocentrolide, Hemolysins-1 and hemolysin-2, saxitoxin, neosaxitoxin, gonyautoxin, tetrodotoxin, ptychodiscus brevis toxin and theonellamide F. According to their mode of action, these toxins are classified into different categories such as cytotoxin, enterotoxin, hemorrhagic toxin, hepatotoxin, nephrotoxins, presynaptic and postsynaptic neurotoxins, ion-channel and sodiumion binding toxins. It provides an insight into analytical techniques for isolation of toxins and their structural elucidation by different spectroscopic measurement as well as the biotechnological significance with respect to their uses and misuses on human population.