Scientific research has always been concerned with aspects of human health. There are several systems of medicines besides the globally accepted allopathy, which are based on compounds originating from natural products. Recent research has been centred around validation of the traditional knowledge on medicinal products. The traditional systems in India, China and forklore medicines in other parts of the world have indicated the potential of natural products consist of various chemical compounds that could be used as drugs. The search for drugs against five major dreadful diseases namely, cancer, AIDS, heart disease, diabetes and pulmonary disorders that attack the present day human from natural products has been in progress for some time. Microbes, plants and animals are the sources of natural products. In the past five decades, the research on bioactive chemicals from marine algae has been incited and several compounds with biological activity were isolated from algae. Generally, these are secondary metabolites produced for chemical defence against the biotic pressure of predators, consumers and epibionts. These potential drugs are now attracting considerable attention from the pharmaceutical industries due to the necessity of identifying substances that could be utilized for novel therapeutic purposes. Several compounds such as alginate, carrageenans, sulphated and halogenated polysachcharise and other derivatives have been shown to provide drugs that could be antiviral, anticancer and antimicrobial. The present account is on the potential of marine macro-algae for medicinally important products.