A large area of earth surface is covered by ocean and it has a diverse range of flora and fauna. A variety of secondary metabolites are produced by them for their specific purposes, which includes protection from predator, reproduction etc. Produced secondary metabolites comprise from simple molecules to complex molecules in terms of skeletal architectures. A large number of marine natural products have been isolated, in which a considerable percentage belongs to organohalogen compounds. In the category of organohalogen compounds, a major portion (approximate 50%) contributed by organobromine compounds and most of them are alkaloids. These compounds ranging from pyrrole, pyridine, pyrimidine, quinoline, isoquinoline to indole, steroid, guanidine, styrene and pyridoacridine. The isolated marine brominated alkaloids exhibited a wide range of biological activity profile like cytotoxic, antiviral, antifungal, antibacterial etc. and some of them are very important from pharmaceutical aspects. In recent past, many pharmaceutically important natural products have been isolated from the marine bryozoans and marketed as drugs and some are in clinical trials. Still in the search of new chemical entities of biological importance with novel mode of actions, the isolation of new marine natural products is continuously growing with a speedy rate. In this chapter, the importance and the key aspects of marine brominated alkaloids have been discussed. © 2015 by Nova Science Publishers, Inc. All rights reserved.