Marine organisms have been extensively explored for the last several decades as potential sources of novel biologically active compounds, and extensive research has been conducted on lectins. Lectins derived from marine organisms are structurally diverse and also differ from those identified from terrestrial organisms. Marine lectins appear to be particularly useful in some biological applications. They seem to induce negligible immunogenicity because they have a relatively small size, are more stable due to extensive disulfide bridge formation, and have high specificity for complex glyco-conjugates and carbohydrates instead of simple sugars. It is clear that many of them have not yet been extensively studied when compared with their terrestrial counterparts. Marine lectins can be used to design and develop new potentially useful therapeutic agents. This review encompasses recent research on the isolation and identification of marine lectins with potential value in medicinal applications.