Spirulina spp. and its processing products are employed in agriculture, food industry, pharmaceutics, perfumery and medicine. Spirulina has several pharmacological activities such as antimicrobial (including antiviral and antibacterial), anticancer, metalloprotective (prevention of heavy-metal poisoning against Cd, Pb, Fe, Hg), as well as immunostimulant and antioxidant effects due to its rich content of protein, polysaccharide, lipid, essential amino and fatty acids, dietary minerals and vitamins. This article serves as an overview, introducing the basic biochemical composition of this algae and moves to its medical applications. For each application the basic description of disease, mechanism of damage, particular content of Spirulina spp. for treatment, in vivo and/or in vitro usage, factors associated with therapeutic role, problems encountered and advantages are given.