Spirulina is an important source of phycocyanin. Phycocyanin has antioxidant, anti-tumorous, anti-inflammatory and hepatoprotective properties. Also natural pigments are gaining much importance in the present day food colourant industry because of the increasing awareness of the harmful effects of synthetic food colourants. As a prerequisite for large scale production in a heterologous host, the important genes involved in the phycocyanin biosynthetic pathway are characterized.