Promising biological activities and excellent resource of guanidine containing natural product has made marine organisms a major centre of attraction of chemists and biologists to explore their drug potential. In this review biological activity of guanidine alkaloids derived from marine organisms are discussed, which are characterized NMR and mass spectroscopy. Cytotoxic and antimalarial activities are compared for different guanidine alkaloids isolated from Monanchora sp. is widely discussed in this review. © 2020 Elsevier Ltd. All rights reserved.