Fur (Ferric uptake regulator) is a DNA-binding protein which represses the transcription of iron-regulated promoters using Fe2+ as a cofactor. In Gram negative bacteria, fur controls the expression of toxins and virulence factors when facing iron-stress. Iron is a key element limiting the growth and proliferation of phytoplankton. We have cloned the fur-gene from the cyanobacterium Synechococcus PCC 7942, applying the polymerase chain reaction (PCR) technique. The DNA fragments amplified encodes a Fur-type protein, which conserves the main motifs found in the family of Fur proteins. Recombinant Fur protein was successfully overproduced, reaching about 15 % of the total protein content. Also, a Fur protein was identified in the filamentous, nitrogen-fixing cyanobacterium Anabaena PCC 7120.