Phycobiliproteins, which include phycocyanin, allophycocyanin and phycoerythrin, are the group of colouredaccessory photosynthetic pigments present in cyanobacteria (blue-green algae). Pseudanabaena is a genus ofmicroscopic cyanobacteria, cosmopolitan in distribution and known to be rich in phycoerythrins. Cyanobacteriaare photosynthetic organisms, thus, one of the factors that influences their metabolism is the quality andquantity of incident light. In order to determine the production of phycobiliproteins (mainly phycocyanin andphycoerythrin) in this genus, the quantity of these pigments was investigated in two different strains ofPseudanabaena, P. catenata USMAC16 isolated from an Arctic location (Svalbard) and P. amphigranulataUSMAC18 from a tropical location (Tasik Harapan, USM, Malaysia). The aims of this study were twofold. First,to determine the influence of different light wavelengths (white, green and red) and exposure duration (photoperiodof 12–24 h (h)) on phycocyanin and phycoerythrin production in the two strains. Second, to comparethe production of phycobiliprotein between the two strains. Highest phycocyanin production was obtainedunder red light, while phycoerythrin production was highest under green light. Highest production was achievedwith photoperiod 24:00 h L:D (L: light, D: dark) in the polar strain and 12:12 h L: D in the tropical strain. P.catenata (Arctic strain) was a good producer of phycoerythrin when grown under green light.